BORTH COASTAL DEFENCE SCHEME: PHASE 1, · PDF fileapproximate area of shingle bank ......

BORTH COASTAL DEFENCE SCHEME: PHASE 1, BORTH, CEREDIGION:

ARCHAEOLOGICAL WATCHING BRIEF

Prepared by Dyfed Archaeological Trust For: BAM Nuttall Ltd

DYFED ARCHAEOLOGICAL TRUST

RHIF YR ADRODDIAD / REPORT NO. 2012/13 RHIF YR DIGWYLLIAD / EVENT PROJECT NO. 102640

Rhagfyr 2012

December 2012

BORTH COASTAL DEFENCE SCHEME: PHASE 1,

BORTH, CEREDIGION:


Gan / By

James Meek

Paratowyd yr adroddiad yma at ddefnydd y cwsmer yn unig. Ni dderbynnir cyfrifoldeb gan Ymddiriedolaeth Archaeolegol Dyfed Cyf am ei ddefnyddio gan unrhyw berson na phersonau eraill a fydd yn ei ddarllen neu ddibynnu ar

y gwybodaeth y mae’n ei gynnwys

The report has been prepared for the specific use of the client. Dyfed Archaeological Trust Limited can accept no responsibility for its use by any other person or persons who may read it or rely on the information it contains.

Ymddiriedolaeth Archaeolegol Dyfed Cyf Neuadd y Sir, Stryd Caerfyrddin, Llandeilo, Sir

Gaerfyrddin SA19 6AF Ffon: Ymholiadau Cyffredinol 01558 823121 Adran Rheoli Treftadaeth 01558 823131

Ffacs: 01558 823133 Ebost: [email protected] Gwefan: www.archaeolegdyfed.org.uk

Dyfed Archaeological Trust Limited The Shire Hall, Carmarthen Street, Llandeilo,

Carmarthenshire SA19 6AF Tel: General Enquiries 01558 823121

Heritage Management Section 01558 823131 Fax: 01558 823133

Email: [email protected] Website: www.dyfedarchaeology.org.uk

Cwmni cyfyngedig (1198990) ynghyd ag elusen gofrestredig (504616) yw’r Ymddiriedolaeth. The Trust is both a Limited Company (No. 1198990) and a Registered Charity (No. 504616)

CADEIRYDD CHAIRMAN: C R MUSSON MBE B Arch FSA MIFA. CYFARWYDDWR DIRECTOR: K MURPHY BA MIFA

Borth Coastal Defence Scheme: Phase 1, Borth, Ceredigion: Archaeological Watching Brief

Dyfed Archaeological Trust DAT Report No. 2012-13



CONTENTS

SUMMARY 1

INTRODUCTION 2

Project background 2

Site Location 2

Proposals 2

Report outline 3

Abbreviations 4

Illustrations 4

Timeline 4

SCOPE OF THE PROJECT 7

ARCHAEOLOGICAL, HISTORICAL AND GEOLOGICAL BACKGROUND 8

Archaeological and Historical Background 8

Geological Information 12

Archaeological Research Framework 13

IMPACT ASSESSMENT AND PROPOSED MITIGATION 15

Existing Knowledge of Site Conditions 15

Predicted Impacts (taken from WSI) 15

WATCHING BRIEF RESULTS 17

Watching Brief Methodology 17

Groyne 1 18

Groyne 2 21

Breakwater 2 22

Breakwater 1 29

The Offshore Reef and Causeway 38

CONCLUSIONS 40

The Design and Implementation of the Archaeological Works 41

Archaeological Conclusions 42

Recommendations for dealing with similar sites in the future 43

REFERENCES 45

APPENDIX 1: A Pollen Analytical Assessment of Sixteen Sub-Samples From Borth, Mid Wales. 46

APPENDIX 2: Assessment Of Samples For Tree Ring

Analysis And Species Identification 52



FIGURES

Figure 1: Location plan of site based on the Ordnance Survey 5

Figure 2: Plan showing finished locations of coastal defence features, including Off shore Reef, Groynes, Breakwaters and approximate area of shingle bank replenishment 6

Figure 3: Detail of Breakwater 2 and locations of peat beds and submerged forest 25

Figure 4: Detail of Breakwater 1 and locations of peat beds and submerged forest 1 35

PHOTOGRAPHS

Photo 1: Extensive exposure of submerged forest deposits at the northern end of Borth beach in March 2010 9

Photo 2: Eastern end of Groyne 1 18

Photo 3: View east towards area of Groyne 1 19

Photo 4: View north across working area of Groyne 1 19

Photo 5: Excavation of western end of Groyne 1 20

Photo 6: Sands and gravel layers above clay deposits within western end of Groyne 1 20

Photo 7: Initial spoil heap with clay deposits removed from the footprint of Groyne 1 21

Photo 8: View east towards area of Groyne 2 during construction 22

Photo 9: Area of peat exposure in the centre of Breakwater 2 where palaeo-environmental sampling was undertaken 23

Photo 10: Excavated area through peat and clay deposits 23

Photo 11: Column sample tins within exposed section 24

Photo 12: Excavation of area of Breakwater 2 26

Photo 13: Laying of geo-textile membrane in base of excavated area 26

Photo 14: Placing of larger stones in the base of the excavated area 27

Photo 15: View east across centre of Breakwater 2 28

Photo 16: Excavation of area within Breakwater 2 showing water-filled excavated area 28

Photo 17: Spoil heap of clay and peat material removed from the foundation area of Breakwater 2 and clays from the groynes 29

Photo 18: Extent of peat beds over area of Breakwater 1 30

Photo 19: Peat deposits within area of Breakwater 1, showing pockmarked surface, facing east 30

Photo 20: Large area of relatively flat peat deposits within area of Breakwater 1, showing timbers and tree stumps 31

Photo 21: Detail of an area of circular marks which could represent animal footprints 31

Photo 22: Linear track across surface of peat 32



Photo 23: Four holes formerly excavated through the peat deposits within the area of Breakwater 1 33

Photo 24: Areas of clay exposed at the same level as peat deposits 34

Photo 25: Fallen tree within area of Breakwater 1 34

Photo 26: Area of Breakwater 1 in August 2011 showing that the peat deposits had been completely covered in sand 36

Photo 27: Excavated trench through peat and clay deposits in area of Breakwater 1 36

Photo 28: Recording of excavated section through peat deposits in area of Breakwater 1 37

Photo 29: Numbered tree stumps removed from area of Breakwater 1 37

Photo 30: Removal of large fallen tree from area of Breakwater 1 38

Photo 31: Constructing the causeway 39

Photo 32: Constructing the offshore reef from the causeway 39

Photo 33: View east towards completed Groyne 1 40

Photo 34: Western part of completed Breakwater 1 40


Dyfed Archaeological Trust DAT Report No. 2012-13 1



SUMMARY

An archaeological watching brief was undertaken during groundworks associated with the construction of the Phase 1 Coastal Defences at Borth, Ceredigion (NGR SN 6070 8940; Planning Application A100445CD). The beach at Borth contains archaeologically significant remains of peat deposits and submerged forests. The significance of these remains around the Welsh coastline has been highlighted in recent studies and publications.

A condition was placed on the planning application for a watching brief during the construction works. This may have been due to the fact that the significance of the deposits was not highlighted at an early enough stage for the planners, designers and developers to put in place more robust mitigation. The peat beds and submerged forest were not seen as a factor in the design of the defences.

Dyfed Archaeological Trust Field Services were commissioned to undertake the watching brief at the start of the construction works. Through discussion with the developers an agreed Written Scheme of Investigation was prepared for the watching brief methodology and which also included a scheme of palaeo-environmental and dendrochronology sampling of the peat beds and submerged forest, undertaken by University of Wales Lampeter Archaeological Services (UWLAS).

The construction methodology for the coastal defences was severely restricted by tidal movement, giving only small windows of construction time each day. As such excavation of the footprints for the structures was done in small stages, excavated rapidly, laid with a geo-textile membrane and then large base stones placed within. Such work involved a large number of machines within fairly confined working areas. It was determined that the watching brief would be mostly quite ineffective and only intermittent visits were carried out.

Through agreement with developers and on-site contractors, two test pits were excavated for palaeo-environmental sampling within the largest areas of peat deposits within the footprints of Breakwater 1 and 2. Initial assessment of these remains has provided an indication of the changing environment in this area during the later Mesolithic through to the early Bronze Age when the land became inundated by the sea. In the area of Breakwater 1 were a number of tree stumps, which were numbered and surveyed by the site contractors prior to being removed and placed elsewhere on the beach for dendrochronology sampling by UWLAS. Full analysis of both the palaeo-environmental remains and dendrochronology samples has not been undertaken as yet.

Although the methodology for the archaeological recording has not been considered ideal, it has highlighted that any such remains should be identified and investigated at the outset of the design of the coastal defences. It is hoped that lessons learnt from this project will assist in developing archaeological recording methodologies in the future which will provide more adequate consideration and analysis of such remains on any future foreshore developments throughout Wales.



INTRODUCTION

Project Background

Ceredigion County Council (CCC) has been granted planning permission and marine consents to construct a coastal defence scheme at Borth, Ceredigion (NGR SN 6070 8940; Planning Application A100445CD). BAM Nuttall were appointed as main contactors to deliver the project.

This report has been prepared by Dyfed Archaeological Trust Field Services (DAT-FS) on behalf of BAM Nuttall to present the results of the archaeological watching brief undertaken during groundworks associated with the construction of the Borth Coastal Defence Scheme: Phase 1.

The Borth Coastal Defence Scheme: Phase 1 comprises the following elements:

• A new offshore Multi Purpose Reef (MPR) at Lower Borth;

• Two 60m long rock groynes along the Lower Borth village frontage;

• Two rock breakwaters along the Lower Borth village frontage;

• Removal of existing timber groynes – to be removed as new rock groynes and breakwaters are constructed;

• Beach nourishment with shingle and sand along the Borth frontage.

An Environmental Statement (ES) has been prepared by Atkins in support of the planning application for the coastal defence scheme, which included a chapter on Archaeology and Cultural Heritage (Atkins 2010). The ES considered the potential impacts of the whole Scheme area from Lower Borth to Ynyslas (Phase 1 and Phase 2).

Site Location

The site area is located on the beach on the seaward side of Lower Borth village, roughly between NGR SN 6071 9010 to SN 6052 8886 (Figures 1 and 2). This covers the majority of the area of the Lower Borth village frontage. This constitutes the area of the Phase 1 part of the Coastal Defence Scheme, and the area of the watching brief. The remaining area from the Lower Borth village frontage to Ynyslas represents the Phase 2 scheme of the defences. No decisions on the Phase 2 scheme have been made as yet.

Proposals

The following presents summaries of the eventual construction methodology that was used for the construction of the various coastal defence elements, based on site information and that laid out within the ES (Atkins 2010). The locations of the features shown on Figure 2 are based on the original plans as supplied by BAM Nuttall.

Multi Purpose Reef (MPR)

The MPR is located around 300 - 400m offshore of Lower Borth. The plans illustrate the reef is in two parts with a small oval area to the south and a larger almost kidney shaped reef on its northern side (see Figure 2). The configuration of the MPR is designed to reduce wave action reaching the shore behind the reef, maintaining the salient and shingle ridge, which act as the primary defence for the village. Additionally, the shape should improve the consistency and quality of the surf around the reef at certain states of the tide.



The MPR was constructed using large rocks which were placed on the seabed by excavators to build up the required shape. The larger rocks used for the base of the MPR were transported via ship and barge. Further rock was stockpiled on land and brought out to the MPR via a temporary causeway constructed of rock leading out from Lower Borth village seafront

Rock Groynes

The two new rock groynes located on the Lower Borth village frontage aim to control the longshore movement of shingle and help control the shape of the beach by holding the shingle against the timber breastwork. The rock groynes replaced a number of timber groynes. The southern rock groyne (Groyne 1) was the first to be constructed.

The groynes were constructed of large rocks, with the lowest layer below the level of the beach. The shape of the groynes were laid out and excavated in stages, with areas being excavated to formation level by large, tracked mechanical excavators. The base of the excavated area was then covered with a thick, permeable geotextile membrane. Rocks were then placed on top of this and gradually built up to form the shape and profile of the finished groyne. The footprint area of each rock breakwaters was approximately 325m2.

Rock Breakwaters

Two rock breakwaters were built as part of the Phase 1 works at Borth. The northern breakwater (Breakwater 2) was constructed first. The rock breakwaters will work with the rock groynes to control the longshore movement of shingle and hold the shingle against the timber breastwork.

The method of construction of the breakwaters was much the same as for the groynes, although constructed over far longer periods and in more stages due to tidal constraints. The footprint area of each rock breakwaters was around 570m2. The depth of excavation needed for the breakwaters was less than that for the groynes, but due to the slope of the beach, these impacted far more on peat and clay levels.

Beach Nourishment

Beach nourishment took place along all of the Lower Borth village frontage. Shingle was imported and placed along the village frontage to create a stable beach. Along the village frontage, the aim was to create and sustain a shingle berm with a minimum crest width of 10m.

Substantial quantities of shingle and sand were imported onto the site area (estimated at approximately 70,000m3 shingle / 126,000 tonnes added to the shingle berm).

Removal of Existing Timber Groynes

The timber groynes along the Lower Borth village frontage were removed by machine. There locations were initially plotted (or presently exist on maps).

Report Outline

This report describes the location of the site along with its historical and archaeological background before summarising the results of the archaeological watching brief based on those results.

Environmental and dendro-chronological assessment has been undertaken of the exposed deposits at Borth by the University of Wales Archaeological Services (UWLAS), the commercial arm of the school of archaeology and ancient history at the University of Wales Trinity St David’s (UoWTSD). During the preparation of this report only the assessment of the dendro-chronological



samples has been completed, with the palaeo-environmental evidence only partially complete. These are included as appendices to this report. The remainder of the assessment and any subsequent scheme of full analysis will be prepared and submitted as separate reports by UWLAS/UoWTSD.

Abbreviations

Regional Historic Environment Record – HER; Primary Record Number – PRN; National Grid Reference – NGR; Scheduled Ancient Monument – SAM; Dyfed Archaeological Trust Field Services – DAT-FS; Written Scheme of Investigation - WSI.

Illustrations

Record photographs are included throughout the text. Printed map extracts are not necessarily reproduced to their original scale and are illustrative only.

Timeline

The following timeline is used within this report to give date ranges for the various archaeological periods that may be mentioned within the text (Table 1).

Period Approximate date

Palaeolithic – c.450,000 – 10,000 BC

Prehistoric

Mesolithic – c. 10,000 – 4400 BC

Neolithic – c.4400 – 2300 BC

Bronze Age – c.2300 – 700 BC

Iron Age – c.700 BC – AD 43

Roman (Romano-British) Period – AD 43 – c. AD 410

Historic

Post-Roman / Early Medieval Period – c. AD 410 – AD 1086

Medieval Period – 1086 – 1536

Post-Medieval Period – 1536 – 1899

Modern – 20th century onwards

Table 1: Archaeological and Historical Timeline for Wales, with the most relevant periods for Borth highlighted



Figure 1: Site Location Plan based on Ordnance Survey 1:50,000 map

Reproduced from the 1995 Ordnance Survey 1:50,000 scale Landranger Map with the permission of The Controller of Her Majesty’s Stationery Office, © Crown Copyright Dyfed Archaeological Trust, The

Shire Hall, Carmarthen Street, Llandeilo, Carmarthenshire SA19 6AF. Licence No AL51842A



Figure 2: Plan showing finished locations of coastal defence features, including Off shore Reef, Groynes, Breakwaters and approximate area of shingle bank

replenishment (stippled grey)



SCOPE OF THE PROJECT

The archaeological condition placed upon the development proposal states that the archaeological mitigation put forward in the Environmental Statement will be adhered to as part of the Coastal Defence Scheme. The Environmental Statement indicated that an archaeological watching brief would be implemented during the construction of the sea defences.

Due to the nature of the development, a licence was also required to comply with the Food and Environment Protection Act 1985: Part II Deposits in the Sea (as amended) in Connection with Marine Construction Works. A licence was granted for the works (Licence 10/51/F) with a more detailed requirement in terms of archaeological mitigation, as laid out in section 9.47:

‘Before work commences on site, a written scheme of investigation shall be agreed with Cadw and Dyfed Archaeological Trust (Curatorial Section) that will detail:

• Required survey to establish the exact positions of known and hitherto unknown wrecks;

• The establishment of exclusion zones around wrecks and fish traps;

• The curation of artefacts during the work;

• Mitigation for disturbance to the peat horizons and submerged forest by minimising excavation and the use of protective membranes to cover exposed areas; and

• The establishment of an archaeological watching brief in appropriate areas during works.’

This document provides the results of the watching brief element of the required works. It is understood that a number of surveys were undertaken by Royal Haskoning in the initial stages of the project for tidal modelling of the shore and beach, including marine geophysical survey. It is understood that this information indicated no wrecks or fishtraps, although analysis and interpretation of this data has not been undertaken as part of the watching brief works. The data should be provided to the Maritime Officer at the Royal Commission for Ancient and Historical Monuments of Wales (RCAHMW) if it has not been already.

At the start of the on-site works a meeting was held between the construction team, Ceredigion County Council and Dyfed Archaeological Trust Field Services to develop a strategy for undertaking the archaeological watching brief and dealing with any exposures of peats or clays of archaeological significance. Prior to February 2010 the extent of peat deposits within the areas of the proposed breakwaters and groynes was uncertain as there was significant sand cover. By the start of the watching brief areas had been revealed at the end of Groyne 1, within Breakwater 2 and a large area covering almost all of the footprint of Breakwater 1.

A written scheme of investigation (WSI) was prepared by Dyfed Archaeological Trust Field Services providing information on how the archaeological watching brief element of the works would be carried out and also how mitigation for the disturbance to peat horizons and submerged forest would be undertaken. This was prepared with assistance from Nigel Nayling and Martin Bates of UoWTSD and Deanna Groom, Maritime Officer with RCAHMW. The WSI was approved by Ceredigion County Council following advice from their archaeological advisors. The WSI was also approved by Cadw in terms of how it addressed the watching brief and mitigation for peat horizons and submerged forest elements of the Marine Licence. The information taken by Royal Haskoning will fulfil the remaining elements of the licence.



ARCHAEOLOGICAL, HISTORICAL AND GEOLOGICAL BACKGROUND

Archaeological and Historical Background

The following information is updated from the Written Scheme of Investigation. The Dyfed Archaeological Trust Historic Environment Record (HER) records 36 known sites of archaeological or historical interest within a 1km radius of the centre of the Borth Coastal Defence Phase 1 area (table 1).

PRN Site Name NGR Description Period

5191 Borth St Matthew's Church

SN 6115 8975 Church Post-Medieval

6094 Gors Fochno SN 60 90 Finds Bronze Age 7298 Wesley Cottage SN 60 89 Cottage Post-Medieval 7375 Borth SN 609 895 Findspot Post-Medieval 8852 Wesley Cottage SN 6084 8934 Dwelling Post-Medieval 9440 Pantyfedwen;

Grand Hotel SN 6083 9013 Hotel Post-Medieval

9676 Borth Bog; Cors Fochno

SN 60 90 Peat Bog Prehistoric

10961 Portuherad; Borth SN 6085 8950 Settlement Medieval 11350 Ynyslas SN 608 902 Finds Prehistoric 13645 Wernleri SN 612 892 Common Land Post-Medieval,

Medieval 13670 Wern Leri SN 609 890 Common Land Post-Medieval,

Medieval 19453 Chapel SN 6090 8999 Chapel Post-Medieval 19454 Capel Libanus;

Gerlan SN 6086 8975 Chapel Post-Medieval

19455 Capel Soar SN 6092 8950 Chapel Post-Medieval 19456 School SN 6085 8950 School Post-Medieval 19457 Capel Siloh SN 6083 8933 Chapel Post-Medieval 19458 School SN 6078 8871 School Post-Medieval 25522 Borth SN 60 89 Lime Kiln Post-Medieval 30761 Borth Beach SN 608 895 Sea Defences, Breakwater Post-Medieval 30787 Quarry SN 6163 8974 Quarry Post-Medieval 31469 Borth Beach SN 6055 9015 Wreck Post-Medieval 31470 Upper Borth SN 608 889 Port Post-Medieval 31474 Borth Beach SN 6078 9017 Sea Defences Post-Medieval 31475 Borth Beach SN 6090 9015 Breakwater Post-Medieval 31476 Borth Beach SN 6090 9012 Breakwater Post-Medieval 31477 Borth Beach SN 6090 9004 Breakwater Post-Medieval 32069 Borth Beach SN 6077 9040 Sea Defences Post-Medieval 45106 Submerged Forest SN 60 90 Submerged Forest Prehistoric 58009 Borth Station SN 60928 90094 Railway Station Listed

Building Grade II Post-Medieval

58010 Angorfa SN 60835 89854 House Listed Building Grade II

Post-Medieval

58011 Morfan SN 60834 89859 House Listed Building Grade II

Post-Medieval

58012 Sabrina Cottage SN 60832 89864 House Listed Building Grade II

Post-Medieval

58013 Saxatile SN 60849 89588 House Listed Building Grade II

Post-Medieval

94900 Borth SN 608 890 Village Post Medieval 94911 Borth Railway

Station SN 6093 9009 Railway Station Post Medieval

94916 Ynys Fergi SN 6127 8959 Farmstead Post Medieval

Table 2: Sites recorded on the HER within a 1km radius of the centre of the site

The majority of these sites lie within the village of Borth and represent buildings and chapels associated with the post-medieval settlement (PRN 94900).



These include an unnamed chapel (PRN 19453), Capel Libanus (PRN 19454), Capel Soar (PRN 19455), Capel Siloh (PRN 1457), two schools (PRN 19456 and 19458), St Matthew’s Church (PRN 5191), Wesley Cottage (PRN 7298/PRN 8852), Ynys Fergi farmstead (PRN 94916) and the Grand Hotel (PRN 9440). A number of post-medieval Listed Buildings are also included, all of which are grade II listed such as Borth Railway Station (PRN 58009/PRN 94911) and a number of domestic houses including Angorfa (PRN 58010), Morfan (PRN 58011), Sabrina Cottage (PRN 58012) and Saxatile (PRN 58013). A post-medieval quarry (PRN 30787), a lime kiln (PRN 25522) and the Upper Borth port (PRN 31470) are also recorded. None of the above sites have been directly affected by the coastal defence scheme works. A post-medieval wreck site is recorded at the northern extent of the Phase 1 Borth Coastal Defence Scheme (PRN 31469). The site was not affected by the coastal defence scheme works.

The medieval settlement at Borth, called Portuherad, was located to the east of the Phase 1 area lying within the existing layout of the town (PRN 10961). An area of common land associated with both the medieval and post-medieval settlements at Borth exists to the east of Borth, known as Wernleri or Wern Leri (PRN 13645 / PRN 13670). Again these sites were not directly affected by the coastal defence scheme works.

Photo 1: Extensive exposure of submerged forest deposits at the northern end of Borth beach in March 2010 (photo Nigel Nayling )

The most significant of the archaeological sites recorded on the HER are those of prehistoric date which lie on the foreshore. The most relevant to the coastal defence scheme are the submerged forest and peat beds that run along the length of the beach (PRN 45106). These deposits are significant both from an archaeological, palaeo-environmental and geological aspect. The peats and submerged forest are a remnant of low-lying land that was inundated by the sea between the Mesolithic and Bronze Age periods. These deposits at Borth have



been subject to previous analysis and it seems that the foreshore was inundated over a period of a few thousand years.

The archaeological significance of the submerged forests has been summarised within the Lost Lands of Our Ancestors publication prepared as part of the West Coast Palaeo-landscapes of Wales project prepared by Dyfed Archaeological Trust, which is presented below:

The remnants of fallen trees and stumps around the coastline are perhaps the most enticing evidence we have for the existence of long lost lands. They offer a tangible link to our ancestral landscape and have helped inspire numerous myths and legends of cities and countries swept away by the sea. Indeed, before their true nature was understood, they were believed to be the result of the biblical flood and were referred to as ‘Noah’s Trees’. They are revealed at low tide at many locations around the Welsh coast, from Rhyl and Abergele in the north, Borth and Newgale in the west to Amroth and Newport in the south. The preserved stumps of willow, hazel, oak, pine and birch are evidence of former woods and forests swamped by the encroaching tides and irrefutable testimony to the devastating effect of climate change.

The tree stumps are rooted in peat levels lying below the marine sand and have been preserved by the continuous waterlogged conditions. The sites around the Welsh coast do not represent a single phase of inundation. The radiocarbon dates from the trees at Ynyslas, Cardigan Bay, suggest that they died around 5,500 years ago, while those just over a kilometre to the south at Borth died some 2,000 years later. The remains of animals have been excavated from the deposits around the tree stumps, including auroch, red deer and brown bear from Whitesands and pig from Lydstep, both in Pembrokeshire. Although observed and commented upon through the centuries, including by Gerald of Wales in 1188 and Samuel Pepys in 1665 no serious study of the submerged forests was made until 1913 when Clement Reid, a geologist, published a book on the subject. His 'Submerged Forests' was the first survey to put these trees into a wider archaeological context and to argue conclusively that they were the result of a rise in sea level. (Murphy 2011)

The northern end of Borth beach, towards Ynyslas has extensive remains of a submerged forest, with a fairly dense layout of tree stumps visible at low tide when sand levels are low (Photo 1). These appear to date from towards the end of the Mesolithic period (c.5000BC).

The peat deposits and submerged forest from the part of the beach within the area of the Phase 1 Borth Coastal Defence Scheme appear to be of later date. Work has been previously undertaken within this area by Heyworth (1985) as part of a PhD thesis which recorded the presence of tree stumps within the Phase 1 area, mostly in the locations near to the two breakwaters and also the northern of the two groynes. The tree stumps were located to the west of these coastal defensive features. The peat deposits here are thought to be more fragmentary than the deposits to the north, although the exposures seen during the watching brief indicates that large extents of peat did still survive buried beneath the sand. Dating of the peat deposits in this area suggest they are of Neolithic date (between c.4000 – 3000BC).

At the southern end of the beach further peat deposits have been recorded by Heyworth (1985). These deposits lie outside of the Phase 1 Borth Coastal Defence Scheme area. During the preparation of this report, human and animal footprints as well as probable archaeological features were recorded in an area of peat exposure to the south of the Phase 1 Borth Coastal Defence Scheme. A subsequent phase of excavation and survey was undertaken of these deposits early in 2012 by the University of Wales Trinity St David with assistance from Swansea Metropolitan University and Royal Commission on the Ancient and



Historical Monuments of Wales (RCAHMW). A report on the results of these investigations is in preparation, but information was not available to include any further detail here. The deposits in the southern part of the beach are thought to date to the Bronze Age (c.2000BC).

This submerged land would have originally been established during the last Ice Age, which ended some 12000 years ago. The lands seem to have been good hunting grounds for Mesolithic hunter/gatherers. The land was evidently waterlogged enough to enable peat levels to become established. Following the end of the last Ice Age ice sheets receded and sea levels rose and these low lying lands around the coastal margins became inundated. The apparent late date of the final inundation at Borth during the Bronze Age would suggest that other factors delayed the progress of the sea. It is possible that this could have been due to a large land form, sand bar or similar which slowly eroded over a few thousand years, eventually letting the sea break through and cover the land to form the coastline, roughly as exists today. It is notable that at Borth there is still a low lying bog on the eastern side of the town, which would become quickly inundated in the event that the existing sea front were breached.

At Borth prehistoric finds have been recovered from these deposits within the Phase 1 area and on the coastal edge (PRN 11350), including flint objects and animal bones. Bronze Age finds have also been recovered from within the Phase 1 area (PRN 6094). It is uncertain if any of these finds have been accurately located or whether they were found securely within peat deposits. The recent investigation to the south of the Phase 1 area has recorded heat cracked stone, suggesting human activity. These may have been associated with a burnt mound, a relatively common feature of the Bronze Age, representing the remains of discarded stones that had been originally heated in a bonfire, before being plunged into water (or having water tipped upon them). This would either cause the water to boil and stay boiling for some time (where they were dropped into a water trough or similar) or would create steam for food processing, cleansing processes or possibly for manufacturing processes.

Borth Bog lies to the east of the Phase 1 area, a bog which formed following the submerging of the above forests and natural development of the shingle bank which presently lies on the foreshore, creating the wetland bog area behind (PRN 9676). Excavations within the bog area have also identified timber walkway structures of early medieval/medieval date. Evidence for prehistoric copper processing has been identified and also late prehistoric/Roman lead processing, with large amounts of slag being noted. These industrial process have left clear palaeo-pollution signatures in the peat deposits. Such remains could be present within the submerged forest and peat beds on the foreshore.

A number of records relating to coastal defences are also recorded on the HER, including the existing breakwaters (PRNS 31475, 31476, 31477 and 30761), and other sea defences (PRN 31474 and PRN 32069). The ES notes that the earliest record of man-made defences at Borth date from the 1930s. The present defences consisting of an intermittent low concrete seawall and timber breastwork in places topped with concrete capping beams. The natural shingle ridge constitutes the main defence line for much of the frontage, with a number of timber groynes which were added to control the movement of shingle. The ES states that most of these defences are in a state of disrepair and are at the end of their useful life, and hence the need for replacement coastal defences to protect Borth from rising sea levels and storm events.



Geological Information

The following section is taken from the ES (Atkins 2010; Appendix C- Geology, Coastal Processes & Long-term Geomorphological Assessment).

Baseline Geology: Introduction

The geological features of interest in close proximity to the proposed site are of national importance as they provide records spanning 7,000 years of coastal and environmental changes during the Holocene in Wales and as such are well described and documented (Matthews, B, 1997a). The cliffs between Clarach in the south and Upper Borth are also important as the exposures describe the Caledonian mountain building episode in this region (CCW, sine data).

Geological Designation

The proposed site is located adjacent to two SSSI’s, designated under the Wildlife and Countryside Act 1981 (as amended). The sites are Dyfi SSSI - located 1.5km to the north of Borth and Borth - Clarach SSSI - located 0.1km to the south of the proposed works and includes the Craig-y-Delyn cliffs.

The geological and geomorphological features of Borth Bog and of the submerged forest are also recognised and the composite area between Borth and Ynyslas constitutes a Geological Conservation Review site (GCR). A GCR site is a site that displays sediments, rocks, fossils, and features of the landscape that make a special contribution to understanding the geological history of Britain.

The former forest embedded in peat is exposed on the lower foreshore halfway between high and low tide marks at Ynyslas at approximately -1mOD and along most of the Borth Frontage and is best visible at low tides during winter following severe storms. Individual tree stumps and trunks also scatter the lower foreshore. Boreholes taken across the site have revealed the forest beds as well as various kinds of peat also underlie Borth Bog inland (Mathews, B, 1997).

Although the designated sites do not extend along the proposed area of the Scheme for Phase 1, the forests tree trunks and stumps embedded in peat are present in Phase 1. It is said that the area provides a near continuous sequence of geological evolution. At particular risk from the development are the embedded forest and peat deposits as they are located in or near the extent of the proposed scheme.

Holocene Deposits

The Dyfi Estuary formed during the last major glaciation by glacial erosion of the existing river valley, which filled with glacial sediment (Halcrow, 2006); (Robins, 2009). The current landscape in the valley, including the frontage of Borth and Ynyslas, Borth Bog and the Dyfi Estuary, is a testimony of the changes that occurred during the Holocene Epoch. The bottom of the geological succession comprises thick deposits of marine and estuarine silty clays and is overlain by a layer of reed peat and by a submerged forest bed.

The Holocene Epoch began 10,000 BP and was characterised by a continuation of the warming which had commenced earlier during the Late Devensian. Local alternations of coastal peat beds and marine clay record a progressive rise in sea-level during this period interceded by short marine regressions.

The last 7000 years of frontage development follows the chronology below:

• A transition between a marine and terrestrial environment occurred around 6,500BP caused by a localised sea-level regression or by a relative decrease of sea-level caused by the isostatic rise of the coast. This resulted in the deposition of the blue-gray blue Scrobitularia clay.



• Also around that time, coastal conditions stabilised and a sand and shingle beach started to develop under longshore drift influence. A protective barrier located approximately 1km seaward from the current position was created from the existing Craig-y-Delyn cliffs to the then mouth of the estuary and supported the development of a terrestrial environment in its lee.

• The subsequent development of reed, followed by oak and pine forests (also alder, hazel and willow), testifies to a period of coastal stability around 6,000 – 5,500 BP (dated by pollen analysis and radiocarbon testing).

• By 4,700 BP, much of the forest growth had stopped, indicating the transition between the terrestrial and marine environment in response to rising sea levels. Trees near the southern end of the area died much later, approximately 3,900 years ago.

• By around 4,500 BP Sphagnum peat overwhelmed the forest and started to accumulate where Borth Bog currently lies. This accumulation occurred under the joint effect of the maintenance of the barrier beach, separating the coast from the hinterland, and the development of humid conditions, which were probably exacerbated by a period of intense rainfall or sea-level rise. Since this time, Borth Bog has continued to develop into one of the largest and finest raised peat bogs occurring near sea level anywhere in the British Isles.

• The coastal barrier has actively rolled landward from 4,000 BP at a rate of 0.25m/yr and probably took its present position around 3,500 BP. The orientation of the fallen trees in the fossilised forest, in a WSW-ENE direction, is consistent with exposure to south-westerly winds.

• A wedge of estuarine-marine silty clay in the peat along the northern edge of Borth Bog may demonstrate a later marine incursion, lasting from 2,900 to 1,750 years BP.

Archaeological Research Framework

The site has the potential to provide information on a number of the themes highlighted within the Archaeological Research Framework for Wales (see http://archaeolog.org.uk), specifically for the Maritime and Coastal section. All of the theme outlined below should be addressed during fieldwork and post-excavation analysis of the site. The relevant document which outlines the Maritime and Coastal framework can be viewed at:

http://www.archaeoleg.org.uk/pdf/maritime/VERSION%2001%20MARITIME.pdf

The main theme highlighted in the document which archaeological works associated with the Phase 1 Coastal Defences can address is Early Prehistoric Colonisation and Exploitation. Results have the potential to answer a number of the following questions raised in the document:

How did the Welsh coastline alter during the early prehistoric periods?

Using geophysical survey techniques, can we predict the positions of potential early prehistoric settlement?

How were ancient coastal and marsh inter-tidal areas exploited in these periods?

What is the extent of the potential for survival of deposits containing archaeological and environmental evidence for these periods?



The document notes that ‘The mapping of the coastline of Wales in the early prehistoric periods as it changed through time as sea levels rose requires considerable further study. As survey becomes more sophisticated, this will enhance our understanding of early prehistoric colonisation and exploitation, from the Palaeolithic, Mesolithic and Mesolithic/Neolithic overlap periods.’

The document states in conclusion that future archaeological works should aim to address the following:

To understand the early prehistoric colonisation and exploitation of the coastline of Wales as it changed through time, by studies of the terrestrial evidence and associated submerged landscapes.



IMPACT ASSESSMENT AND PROPOSED MITIGATION

Existing Knowledge of Site Conditions

Previous archaeological investigations undertaken on the foreshore at Borth have demonstrated the presence of extensive peat beds and submerged forest within the Phase 1 area of the Borth Coastal Defence Scheme. This has included identification of exposures of peat, tree stumps, large trunks and exposed clay surfaces (the levels beneath the peat deposits).

Borehole information supplied by BAM Nuttall indicates that out of 6 boreholes sunk along the upper part of the foreshore, peat deposits were recorded in the most northerly boreholes (BH3A, BH4, BH5 and BH6). Artefacts, animal bones and even archaeological features have been previously recorded within these peat deposits and thus the potential for such to be present within the Phase 1 area was considered likely.

Any such deposits will have been impacted upon by tidal erosion, but as seen along the Welsh coastline, highly significant evidence can still remain. In the summer of 2010 previously unknown human (and animal) footprints were identified within the peat beds at Lydstep in Pembrokeshire.

During the preparation of this report, human and animal footprints as well as probable archaeological features were also recorded in an area of peat exposure to the south of the Phase 1 Borth Coastal Defence Scheme. A subsequent phase of excavation and survey was undertaken of these deposits early in 2012 by the University of Wales Trinity St David with assistance from Swansea Metropolitan University and Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW). A report on the results of this work is in preparation.

It was noted in the WSI that localised impacts will have come from the construction of the existing timber groynes and sea defences constructed along the Borth coastline, although such impacts will be fairly small scale.

Predicted Impacts (taken from WSI)

The proposed Borth Coastal Defence Scheme: Phase 1 will impact upon highly significant buried archaeological, palaeo-environmental and geological deposits associated with submerged land surfaces, where trees have been dated from around 7,000 BP to 4,000 BP.

Excavation in advance of the construction of the stonework groynes will cause significant below ground disturbance within their footprints. The excavations for the groynes could be a number of metres in depth, with deepest works around the edges of the structures (especially the seaward end). Such works are likely to expose, damage or destroy areas of the peat beds and submerged forests within their footprints.

Excavation in advance of the construction of the stone breakwaters is also likely to involve some below ground disturbance (although not as deep as the groynes). The seaward edge of the structures will be the deepest. The breakwaters are located further from the coastal edge where the beach slopes gradually down to the sea. It is likely that buried deposits associated with the peat beds and submerged forests may be relatively shallower in these areas and thus the works will still have the potential to expose, damage or destroy such deposits.

The proposed reef is unlikely to have any immediate physical impacts on any buried deposits, as material used in its construction will be placed on the



existing sea bed. It is not possible to ascertain what the impact would be in terms of changes in tidal movement or scouring adjacent to the reef on underlying deposits – nor would it be possible to mitigate against them at this stage.

Consultation with Palaeo-environmental specialists at University of Wales Trinity St. David has confirmed that the Borth Coastal Defence scheme will impact upon underlying deposits associated with the submerged forests and peat deposits. These have considerable potential for palaeo-environmental evidence, areas of which could be destroyed or damaged by the proposed works.

There is a potential for recovering samples from trees for dendrochronology dating. Column samples should be taken for pollen and other analyses (diatoms, forams etc) and to recover material for radiocarbon dating. Bulk samples of the peat deposits could be taken for insect analysis and study of plant macrofossils.

The site area also has the potential to contain archaeological features and artefacts. To the north of the Phase 1 area a hearth was found within the peat beds (Heyworth 1985) and animal skeletons have been recovered to the south (Taylor 1973). Palaeo-environmental sampling would also be essential within these areas if archaeological features or artefacts are found within the peat beds.



WATCHING BRIEF RESULTS

Watching Brief Methodology

Ground reduction works on the beach were monitored intermittently by a professional archaeologist. Attendance commenced at the start of the excavations for Groyne 1. Due to health and safety constraints from working in a confined area with numerous large mechanical excavators and lorries, the majority of archaeological recording during the watching brief was undertaken remotely from the sides of the excavated areas. Recording was carried out using photographic and written descriptions. Exposures of peat deposits, locations of environmental test pits, tree stumps and the coastal defence structures themselves were surveyed in by the site contractors and the information supplied to Dyfed Archaeological Trust.

Following the first two days of observations it was evident that the working methodology was such that only occasional visits to the site would be needed by an archaeologist. Peat and clay deposits with archaeological potential were only present towards the western end of Groyne 1, over parts of the location of Breakwater 2 and covered a very large area of the footprint of Breakwater 1. No visible peats were present within the footprint of Groyne 2. Lines of communication were established with the site foreman, site contractors and the managers within the site office (with the majority of liaison being with Ray Jones, Senior Agent, BAM Nuttall). This meant that Dyfed Archaeological Trust Field Services could be informed in advance of the commencement of works on the various coastal defence structures to avoid any visits to the site when no works were ongoing or informed if any potentially significant archaeological remains were exposed. This enabled archaeological observation to be targeted on only those areas of interest.

The coastal defence structures were excavated in the order Groyne 1, Groyne 2 and intermittently with Breakwater 2, with Breakwater 1 the final of the observed structures. The replenishment of the shingle bank and construction of the multi-purpose reef was undertaken throughout the duration of the works and was not archaeologically monitored. A stone causeway was constructed projecting from the southern end of the beach out towards the multi purpose reef using imported stone. This allowed machine and pedestrian access out to the area of their construction. The causeway was built directly across the beach and was again not monitored.

Due to the scale of tidal movement of sand and shingle across the beach, the site contractors needed to adapt their construction methodologies to prevent the infilling of excavated areas by the next high tide. To minimise this, stone being used in the construction of the structures was laid around their seaward side to act as a protective wall. As the project developed, excavation of smaller areas for the structures were undertaken to allow immediate covering of the base with geo-textile membrane and laying of the largest stones for their foundations. This was undertaken during each of the intertidal periods so that any sand deposited by the next high tide merely infilled the gaps between the stones as was the intention of the construction method.

Once the foundations of the structures had been constructed, they were then layered with different sized stones until the full height and extent of the structures was completed. Sand and shingle then naturally infilled gaps in the stones and formed around the structures creating the functioning coastal defences.

All of the works, especially those closer to the mean tide mark, were restricted by tidal heights. This meant that the construction of the breakwaters



could only be undertaken for a few hours a day. The shingle bank and causeway to the reefs were worked on during these times.

Groyne 1

Groyne 1 was the first of the four structures to be constructed. It was the southern of the two groynes. Initial excavations for its base were carried out on the day before the archaeological watching brief commenced, although these were then refilled by the tide over night (Photo 2). This led to the changes in methodologies for construction to be implemented.

Photo 2: Eastern end of Groyne 1 after initial excavated area had been re-filled with shingle, with defensive wall of stone being constructed (16/02/2011)

The eastern side of the structure was located at the highest part of the beach slope adjacent to the timber sea wall (Photos 2, 3 & 4). The beach in this area was comprised of layers of shingle on top of sands and gravels beneath. No underlying peat or clay deposits were present at this end of the structure, presumably as the depth excavated was not great enough to reach the clays.



Around the western end of the structure a number of small disparate patches of peat were visible, some with occasional tree stumps and timber within (Photo 3). The peat levels had evidently been significantly eroded in this area. The excavations did reveal clays at a lower depth in this part, but no depths of peat within the footprint of the structure.

Photo 3: View east towards area of Groyne 1, with adjacent areas of peat (16/02/2011)

Photo 4: View north across working area of Groyne 1, highlighting the working restrictions – with numerous machines and incoming tide (17/02/2011)



The construction of the base for Groyne 1 was undertaken over a number of weeks, becoming more dependent upon tidal heights the further west (seaward) it went (Photo 4). As no clear indications of peat were visible within the footprint of the structure and the restrictions with working in small areas with numerous machines, the watching brief was undertaken intermittently (Photo 4).

Photo 5: Excavation of western end of Groyne 1, showing clay layers in base of excavated area (23/02/2011)

Photo 6: Sands and gravel layers above clay deposits within western end of Groyne 1 (23/02/2011)



Photo 7: Initial spoil heap with clay deposits removed from the footprint of Groyne 1 (23/02/2011)

Towards the western end of the structure clay deposits were exposed below the sands and gravel layers (Photos 5 & 6). Further restrictions to observation of the works became apparent at this time, with water filling the areas as they were excavated and the saturated edges of the excavated areas being very unstable. It was confirmed that no clearly defined peat layers survived within the footprint of Groyne 1, although occasional thin lenses of peat were noted. Due to health and safety restrictions these areas could not be accessed for detailed recording, although the information that could have been gleaned from these deposits during the watching brief was minimal. Clays removed from the base of the Groyne were stockpiled off the beach in a contractor’s compound at the northern end of the coastal defence scheme. These were occasionally monitored to determine whether any areas of peat were present in the clay, and whether any artefacts could be retrieved from the spoil tips (Photo 7). No significant archaeological remains were exposed.

Groyne 2

Groyne 2 was located at the most northerly point of the Phase 1 Coastal Defence Scheme. The footprint of the groyne was located adjacent to the timber sea wall and cut through the shingle bank (Photo 8). No areas of peat were known in this part of the beach and none were affected by the excavations for the structure. Clay deposits were present, but their removal was not archaeologically monitored due to the very unlikely presence of archaeological remains. The spoil heap was occasionally walked over to search for artefacts.



Photo 8: View east towards area of Groyne 2 during construction (23/02/2011)

Breakwater 2

Breakwater 2 was located between Groyne 1 and 2, but positioned further seaward than the western ends of the two groynes. The structure was roughly kidney shaped, with its outer curving edge on the landward side. Prior to the commencement of the works it was noted that a large area of peat deposits were present within the footprint of the structure. The outline of the breakwater was marked with stones to confirm the area for foundation excavation (Photo 9). The peat deposits were walked over on a number of occasions to determine the extent of the material, its state of preservation and whether any indications of human activity were visible. The extents of the area of peat were surveyed by BAM Nuttall.

It was agreed with the developer that an initial scheme of palaeo-environmental sampling of the peat deposits should be undertaken prior to the main construction works starting. Dr Roderick Bale of UWLAS visited the site with a few students to assess the peat deposits on 07/03/2012. A methodology for excavation and sampling was agreed with the site contractors and the team returned on 08/03/2012 to take samples of the deposits and record profiles of the peat and clay layers. The area for sampling was chosen as it had the best survival and depth of peat deposits within the footprint of the structure (Photo 9).



Photo 9: Area of peat exposure in the centre of Breakwater 2 where palaeo-environmental sampling was undertaken (07/03/11)

Photo 10: Excavated area through peat and clay deposits (08/03/2011; UWLAS)

The small area was machine excavated under archaeological supervision into the underlying clays to a safe depth (Photo 10). One of the exposed section edges of the trench was cleaned and drawn and written descriptions of the deposits were made. Two column sample tins were then placed in the section to



obtain a complete profile through the deposits, enabling the detailed analysis of pollen remains within the full surviving stratigraphic sequence of the peats (Photo 11). A series of samples from the stratigraphic layers were also removed from the section for further analysis. It was noted that the trench filled with water fairly quickly and that the sides of the trench became unstable quite quickly. The samples were then taken to University of Wales Trinity St David for assessment (Appendix 1).

Photo 11: Column sample tins within exposed section, note the water ingress in the base of the trench (08/03/2011; UWLAS)

Construction work continued on the adjacent areas to the peat deposits before and after the palaeo-environmental sampling, with intermittent observation by an archaeologist. The excavation methodology was similar to that used for the groynes, although the windows for working were far smaller due to the majority of tides covering the footprint of the structure. The works could only be undertaken during the higher tidal ranges, commencing at the moment the tide receded beyond the edge of the structure and finishing when the tide returned. Small areas were machined to the necessary depth, the base covered with a geotextile membrane and then the largest base stones placed on top. This process had to be done rapidly to fit in with tidal movement.



Figure 3: Detail of Breakwater 2 and locations of peat beds and submerged forest



Photo 12: Excavation of area of Breakwater 2 with previously excavated and stoned area in foreground (07/03/2011)

Photo 13: Laying of geo-textile membrane in base of excavated area (07/03/2011)



Photo 14: Placing of larger stones in the base of the excavated area as a foundation for the rest of the structure (07/03/2011)

The eastern side of Breakwater 2, where no peat deposits survived, was quite dry in comparison to that on its western edge, although this may have been as a result of a spell of dry weather. The above photographs 12 to 14 show the excavated area remained quite dry during the foundation construction process. This is in complete contrast to an area on its western side taken later in the same month, which filled with water almost immediately on excavation. Although the excavated areas were constantly pumped out to remove enough water to be able to continue the construction works (Photos 15 & 16), a large amount of water remained within the excavated areas (due to constant water seepage). Disturbed sands and sediments were such that it was not possible to see the base or sides of the excavated areas.

The clays and peat deposits removed from the excavations were added to the stockpile of material within the contractor’s compound in the northern area of the coastal defence scheme. The spoil heap was monitored for artefacts. Some of the larger clods of peat were split open to determine if any artefacts were present such as worked flint or worked wood, but none was found, excluding a single flint flake. This item was a simple waste flake, with no evidence for secondary working. It was of indeterminate date, but most likely of Neolithic or Bronze Age date.



Photo 15: View east across centre of Breakwater 2, showing stones aligned around its edge and pile of stones

in the centre ready for laying within foundations. The flooded area covers the footprint of the structure and the area which was

sampled (05/04/11)

Photo 16: Excavation of area within Breakwater 2 showing water-filled excavated area. The large stones to the right of the photo are those already laid in areas of

the foundations for the structure (05/04/11)



Photo 17: Spoil heap of clay and peat material removed from the foundation area of Breakwater 2 and clays from the groynes (05/04/2011)

Breakwater 1 (Figure 4)

During site visits carried out for the other structures, it was evident that a large expanse of peat was present over the majority of the footprint of the area of Breakwater 1. This Breakwater lay to the southwest of Groyne 1.

During the initial visits to the coastal defence scheme, the area of Breakwater 1 was clear of sand exposing quite a large expanse of peat material with numerous tree stumps. The extent of this exposure changed regularly over the period of the watching brief, but never as large as it was on 16/02/2011 and 17/02/2011 (Photo 18).

In places the surface of the peat exposure was pockmarked with numerous channels and stone holes caused by natural erosion (Photo 19), although in others relatively large expanses of flat peat survived (Photo 20). It was noted that possible animal footprints were visible in the surface (Photo 20 and 21), the marks being roughly 0.06m in diameter.



Photo 18: Extent of peat beds over area of Breakwater 1 (16/02/2011)

Photo 19: Peat deposits within area of Breakwater 1, showing pockmarked surface, facing east (17/02/2012)



Photo 20: Large area of relatively flat peat deposits within area of Breakwater 1, showing timbers and tree stumps, facing west (17/02/2012)

Photo 21: Detail of an area of circular marks which could represent animal footprints (17/02/2012)



A further area within the flat peat surface contained a definite track across its surface. The track appeared to be two parallel lines of imprints in the peat surface, highlighted by the fine sand and silt within their base. The track ran for less than three meters in a north to south direction, with a group of more random marks at its southern end (Photo 22). The track seemingly comprising a collection of roughly round imprints (around 0.15m to 0.20m in diameter) produced by more than one animal following the same path for this length. A collection of more random rounded imprints was present at its southwestern end. If they do indeed represent animal tracks, then the size of the marks suggests a large animal. It is known that a bear footprint was found in the peats recorded by University of Wales Trinity St David in the southern part of the beach (outside the area of the coastal defence scheme) and there is a potential that they could be very eroded remains of bear tracks.

Photo 22: Linear track across surface of peat, with larger rounded imprints on right hand side of photo (17/02/2011)

The interpretation of these marks as animal tracks is by no means conclusive, as many of the more random marks could have been caused by erosion from shingle movement. The linear track was also brought into question as a similar aligned definite tyre track was noted to the south, although this was far more regular and conclusively caused by tyre tread. At the northern end of the track were four holes that had been excavated out of the peat using a



mechanical excavator with a toothed bucket (Photo 23). These holes had not been excavated recently, being quite eroded on their edges. The possibility that the short track was actually caused by the wheeled JCB or similar which excavated the holes should not be discounted. The excavations through the peat may have been associated with previous archaeological investigations on the site. At least one tree stump which had been sawn through for a Dendrochronological sample was present in the area also indicating that this part of the site had been subject to some archaeological recording previously.

Photo 23: Four holes formerly excavated through the peat deposits within the area of Breakwater 1 (17/02/2011)

In some places the underlying clays had been exposed at the same level as the peats, which must indicate that the original ground surface would have been slightly undulating (Photo 24).

As noted above, a number of tree stumps and fallen trunks were present across the footprint of Breakwater 1 which were clearly visible on 16 and 17/02/2011. One of the fallen trees was around 3m in length (Photo 25). Within one week the peat beds and many of the tree stumps had been covered with sand and the areas of possible footprints were not seen again during the course of the watching brief. The area remained covered for the majority of the year (Photo 26)

Due to the extent of the peat deposits and number of tree stumps within the footprint of Breakwater 1 a similar sampling strategy was put in place as had been done for Breakwater 2. The outline of the breakwater was initially marked on the ground and a scheme of palaeo-environmental sampling was implemented. A scheme of Dendrochronological sampling was also put in place.

A single area was identified for sampling before construction works commenced on the structure. The area was machine excavated under archaeological supervision and then one of the long sides of the trenches cleaned, drawn and recorded to provide a detail of the stratigraphic sequence of the deposits (Photos 27 & 28). Two column tin samples were taken, supplemented with samples taken from the layers within the stratigraphic sequence.



Photo 24: Areas of clay exposed at the same level as peat deposits (17/02/2011)

Photo 25: Fallen tree within area of Breakwater 1 (17/02/2011)



Figure 4: Detail of Breakwater 1 and locations of peat beds and submerged forest



Photo 26: Area of Breakwater 1 in August 2011 showing that the peat deposits had been completely covered in sand (30/08/2011)

Photo 27: Excavated trench through peat and clay deposits in area of Breakwater 1 (30/08/2011)



Photo 28: Recording of excavated section through peat deposits in area of Breakwater 1(30/09/2011; UWLAS)

Photo 29: Numbered tree stumps removed from area of Breakwater 1 (30/09/2011; UWLAS)

The tree stumps and larger timbers were removed by machine from the area of Breakwater 1 prior to construction works starting (Photos 29 & 30). The tree stumps were numbered by the site contractors and their locations plotted.



They were then moved to another part of the beach prior to the dendrochronology team from UWLAS identifying the species of the trees and determining if there was a potential for obtaining a Dendrochronological date. Where there was a potential, sawn sections were removed from the trees for analysis.

Photo 30: Removal of large fallen tree (see Photo 25) from area of Breakwater 1 (30/09/2011; UWLAS)

Initial assessment of the palaeo-environmental and dendrochronology samples has been undertaken UWLAS (Appendices 1 & 2), although further assessment including radiocarbon dating and forma/ostracod assessment is awaited. A scheme of full analysis of these samples has not been undertaken.

The Offshore Reef and Causeway

No archaeological monitoring was undertaken during the construction of the offshore reef and connecting causeway from the beach (Photo 31, 32 and cover photo). The majority of the works involved laying of large stones below sea level, whereas the causeway was built directly on the beach, with no excavations for the footings. The larger base stones used in the offshore reef were laid directly from transport ships, with the stones used in the upper layers being transported by road and then taken to the reefs via the causeway.

During one of the later watching brief visits, the completed structures of Breakwater 2 and Groyne 1 were photographed. These showed that the coastal defence structures were already beginning to blend in with the beach. Sand had infilled the bases of the structures and vegetation had started to grow on the stones (Photos 33 & 34).



Photo 31: Constructing the causeway (03/06/2011, BAM Nuttall)

Photo 32: Constructing the offshore reef from the causeway (13/10/2011)



Photo 33: View east towards completed Groyne 1 (30/08/12)

Photo 34: Western part of completed Breakwater 1 (30/08/12)



CONCLUSIONS

The Design and Implementation of the Archaeological Works

The beach at Borth was known to contain archaeologically significant remains of peat deposits and submerged forests. The significance of these remains around the Welsh coastline has been highlighted in recent studies and publications as discussed above.

The extent of these deposits within the Phase 1 area had not previously been accurately surveyed. A number of intermittent research projects had been carried out on some areas of the peat beds. As part of the archaeology chapter for the Environmental Statement prepared for the Coastal Defence Scheme (Atkins 2010) the peat beds and submerged forest were noted, but the significance of the remains was not clearly highlighted. The Environmental Statement indicated that an archaeological watching brief would be implemented during the construction of the sea defences. Unfortunately this recommendation was placed as the condition on planning permission, with no real consideration of the potential impacts to the peat beds and submerged forests.

Dyfed Archaeological Trust Field Services were approached to provide costs for the watching brief. The significance of the archaeological deposits likely to be exposed, damaged or destroyed by the works was highlighted within the fee proposal. A Written Scheme of Investigation (WSI) was prepared by Dyfed Archaeological Trust Field Services for the watching brief and also included a scheme of palaeo-environmental and dendrochronology sampling of the peat beds and submerged forest. This was prepared in consultation with Nigel Nayling and Martin Bates of UWLAS and Deanna Groom, Maritime Officer with RCAHMW.

Due to the nature of the development, a Marine Licence was also required for the development. A licence was granted for the works (Licence 10/51/F) with a more detailed requirement placed upon the development by Cadw in terms of archaeological mitigation, including the need for surveys of the sea bed to determine the presence of any wreck sites or fish traps, and exclusion set up around any such features identified; the curation of any artefacts recovered during the work; mitigation for disturbance to the peat horizons and submerged forest by minimising excavation and the use of protective membranes to cover exposed areas; and the establishment of an archaeological watching brief in appropriate areas during works. Cadw commented that the WSI was adequate for the archaeological watching brief, but that it did not address either the need for surveys for ship wrecks or fish traps nor did it fully address the need to minimise disturbance to the peat horizons or submerged forest. It should be noted that the WSI was prepared immediately before the commencement of the construction works following the design and approval of coastal defence structures. Dyfed Archaeological Trust Field Services did not have any involvement in the design process for the Phase 1 Coastal Defences.

Initial meetings with the BAM Nuttall, Atkins and Ceredigion County Council further highlighted the significance of the deposits and a strategy for recording was put in place. Through the assistance of the site contractors following discussions with Dyfed Archaeological Trust Field Services and UWLAS, it was also possible to undertake the palaeo-environmental and dendrochronology sampling. Unfortunately at this time only the initial assessment of the pollen from the palaeo-environmental samples has been carried out. The full assessment of the dendrochronology samples has been completed.



Archaeological Conclusions

The method of construction for the coastal defence structures was not one that was ideal for archaeological recording. The excavation of the footings of the structures was undertaken using a number of large machines to enable rapid excavation and laying of foundations between the receding and incoming tides. This window of opportunity was smaller depending on the height of the tides and reduced the further to the west the works were undertaken. The excavated areas were also often unstable and filled with water.

It was evident at the very start of the watching brief that the potential for the recording of archaeological remains during the construction process was very limited. It was agreed that only occasional attendance by an archaeologist during the construction works would be necessary, targeting those areas where peat beds or submerged forest remains would be affected. It was also agreed that the scheme of palaeo-environmental and dendrochronology sampling should be undertaken on the two breakwaters, where the greatest areas of peat beds and submerged forest remains would be impacted upon. This was then undertaken with the full cooperation and assistance of BAM Nuttall and the on-site contractors, to excavate and survey the test pits and to also survey in the tree stumps and fallen trees belonging to the submerged forest, prior to them being lifted and moved for later investigation and sampling.

In terms of the success of the watching brief, by having occasional visits to the site, it was possible to monitor changes in the extents of exposure of the peat beds. Typically the largest exposure, with potential animal footprints was visible at the very start of the watching brief, but was not visible to that extent again. BAM Nuttall did survey the peat extents at this time, but unfortunately no detailed recording of the surface of the peats was carried out at this time by the attending archaeologist (as it was mistakenly anticipated that later opportunities would arise to record them). It should be noted that even the largest extents of peat revealed within the Phase 1 coastal defence area were not as great as those that have been seen further north on the beach towards Ynys Las.

A single flint flake was recovered from the spoil heap of clay and peat material that was stockpiled at the northern end of the coastal defence area. The flint flake was not diagnostic and cannot be clearly dated, although a Neolithic or Bronze Age date is likely. The flint flake merely indicates that human activity was present in this area during the prehistoric period, something which has previously been confirmed.

Unfortunately at this time only the initial assessment of the pollen from the palaeo-environmental samples has been carried out (Appendix 1). Further assessment of forams and ostracods is awaited and a number of radiocarbon dates is also left to be done by UWLAS. The initial pollen assessment has indicated a sequence of vegetation development within the peat levels. The earliest information suggests a fen landscape with an abundance of alder growing upon it within the locale of the site area, with oak woodland in the vicinity. The coastline at the time of this earliest pollen information, would have been located a number of kilometres to the west within the Irish Sea, with the site area lying in a fairly low lying waterlogged environment. The samples from Breakwater 2 suggest that at a later date falling water levels may have led to pine trees becoming established within the site area. After this time there is an indication of woodland clearance in the vicinity, very possibly through human activity. Grasses then became established within the area, although woodland was still prevalent in the locale and vicinity. The upper peat levels (latest) contain pollen suggesting that the alder fen woodland re-established itself. This may suggest increasingly wet ground conditions which could be an indicator of the later encroachment of



the sea across the area and establishment of a coastline in a similar location to that which we see today.

Although no radiocarbon dates have been obtained for the palaeo-environmental remains at this time, from previous dates obtained from the deposits on this part of the beach it is likely that the pollen sequence runs from the Mesolithic to Neolithic periods (10,000 - 2300BC). At the end of the last Ice Age, the sea level was perhaps some 40m lower than presently exists, with Borth lying many kilometres inland. As sea levels rose throughout the Mesolithic period, low lying land became inundated by the sea and the coastline moved inland. During this period hunter/gatherers, groups of nomadic humans, would have exploited the land (10,000 - 4400BC), which is likely to have been the alder fen woodland at Borth, as noted above. By the Neolithic period, agriculture and more permanent settlements began to be established. The woodland clearance suggested by the pollen assessment may have been associated with human activity (4400 - 2300BC). Previous radiocarbon dating indicates that the forest at Ynyslas to the north of the site area became submerged around 5,500 years ago (c.3500 BC) and those at the very southern end of the beach some 2000 years later (c.1300BC), during the Bronze Age (2300 - 700BC). It is thus possible that the latest pollen remains recorded within Breakwater 2 may be associated with an increasing waterlogged land surface (alder fen woodland) indicating the start of the inundation of the area by the sea during the late Neolithic period or early Bronze Age.

The full assessment of the dendrochronology samples has been completed, but not the further detailed analysis or dating. Ideally this would be done in conjunction with obtaining radiocarbon dates from at least one of the trees and also tied in with those being obtained for the palaeo-environmental assessment.

Recommendations for dealing with similar sites in the future

The methodology for the archaeological mitigation at Borth is not seen as being ideal. It is considered that in this instance the archaeological remains were considered at a stage too late in the process to be as effective as they might have been. Ideally the significance of the peat beds and submerged forests would have been identified at the start of the project, during the preparation of the Environmental Statement and contributed to the design of the scheme. In the event, the work at Borth has produced very interesting information through the cooperation of BAM Nuttall and the on-site contractors to assist with the archaeological recording strategy.

Following discussions with the Archaeological Coastal Forum Group (including members of Cadw, National Trust, RCAHMW, the four Welsh Archaeological Trusts and UoWTSD) it has been requested that there should be a consideration of how future intertidal developments may be dealt with. The following bullet points are a suggestion as to how archaeological mitigation might be implemented on similar intertidal developments on areas of peat beds and submerged forests in the future. The consideration of the deposits at the outset of the design of any such project is paramount. It is understood that in some cases this methodology for mitigation may not be possible.

• The presence of peat beds and submerged forests identified at the outset of the project;

• Coastal monitoring undertaken over a period of at least 6 months to observe and define possible extents of peat beds and submerged forests, with the results feeding in to the design of the development or coastal defences scheme;



• Where possible, structures to be constructed on the foreshore should be designed to avoid impacting upon these deposits, or minimising any impacts;

• Prior to the commencement of development a scheme of archaeological evaluation of the deposits should be undertaken. This could include observation of the exposed surfaces of any peat beds and initial assessment of tree stumps (identification of species and assessment for suitability for dendrochronology dating). A number of test pits should be excavated through the peats, where they will be impacted upon, to obtain palaeo-environmental evidence for assessment. Radiocarbon dates should be obtained at this stage;

• Should significant remains be identified, such as artefacts or footprints, a scheme of detailed recording should then be implemented. This would include further palaeo-environmental sampling. Alternatively this information may indicate that redesign of the proposals would be appropriate;

• If few or no significant remains are identified then a scheme of intermittent watching brief may be appropriate;

• Full assessment of the palaeo-environmental and dendrochronology samples should then be undertaken, preferably before or during the construction phase in order that if highly significant information is revealed, further sampling can be undertaken; and

• Full reporting and archiving of all results.

In all cases where intertidal development is proposed, it is recommended that some form of detailed geophysical survey of the sea bed is carried out at the early design stage of identify wreck sites or the presence of fish traps. The data and evidence for any possible submerged structures should be made available to the relevant archaeologists (for example Cadw or RCAHMW). Where submerged structures are identified, these should be avoided by any construction works/traffic etc, or if this is not possible, then appropriate schemes of recording should be implemented.



REFERENCES

Atkins 2010, Borth Coast Protection Scheme Environmental Impact Assessment. 28th June 2010; including Appendix C- Geology, Coastal Processes & Long-term Geomorphologic Assessment

Heyworth, A. 1978, "Submerged forests around the British Isles: their dating and relevance as indicators of post-glacial land and sea level changes" in Dendrochronology in Europe, ed. J. Fletcher,Oxford, pp. 279-288

Heyworth, A. 1985, Submerged Forests: A Dendrochronological and Palynological Investigation. Unpublished PhD thesis, University of Wales, Aberystwyth.

Mathews, B., 1997, Ynyslas and Borth - Site Management report series. GCR Block: Pleistocene/Quaternary of Wales

Meek, J., 2011, Borth Coastal Defence Scheme: Phase 1, Borth, Ceredigion: Written Scheme Of Investigation For Archaeological Works, DAT Report February 2011

Murphy, F., 2011, Exploring The Submerged Landscape of Prehistoric Wales, The Lost Lands of Our Ancestors, West Coast Palaeolandscapes Project, Dyfed Archaeological Trust

Robins, P. E., 2009, Development of a morphodynamic model of the Dyfi Estuary to inform future management decisions, CCW Contract Science Report No 898a

Taylor, J. A., 1973, 'Chronometers and chronicles; a study of palaeoenvironments in west central Wales ', Progress in Geography 5, 247-334



APPENDIX 1:

A POLLEN ANALYTICAL ASSESSMENT OF SIXTEEN SUB-SAMPLES FROM

BORTH, MID WALES.

Sarah Jones: University of Wales, Lampeter Archaeological Services

February, 2012

Introduction

This report describes a preliminary palaeoecological assessment of sixteen sub-samples from Borth, mid Wales. The sub-samples were selected from the two test pits excavated within Breakwater 1 (BW1) and Breakwater 2 (BW2) of the Borth Phase 1 Coastal Defence Scheme. The programme of work carried out aims to establish the state of pollen preservation throughout the sedimentary sequences. It outlines the laboratory procedures and discusses the results of pollen analysis.

Laboratory Procedures

Sixteen sub-samples were selected for pollen analysis, eight from both test pits, BW1 and BW2. Samples for pollen analysis were prepared using standard techniques (Moore et al., 1991), including treatment with HCl to remove carbonates, micro-sieving through a mesh aperture of 10µ, HF digestion to remove silicates and acetolysis to digest organic matter. A known quantity of Lycopodium spores were added to each sample to enable the calculation of pollen concentrations within the samples (Stockmarr, 1971). The residues were mounted in safranin-stained glycerine jelly and analysed under a Leica DMR microscope at a magnification of x400, with critical identifications at x630 and, where necessary, under oil at x1000. Pollen was identified using standard pollen keys (e.g. Andrew, 1980; Moore et al., 1991) and type collections. Plant nomenclature follows Stace (1997). The state of pollen preservation is referred to using the categories identified by Jones et al. (2007), e.g. corroded (biochemical deterioration) and degraded (chemical deterioration).

Results

Pollen preservation was very variable, with pollen concentrations diminishing towards the base of both test pit sequences. Assessment level counts of 100 total land pollen (TLP) grains were achieved in all but five samples (BW1/48-49cm, BW1/72-73cm, BW1/78-79cm, BW2/66-67cm and BW2/78-79cm) and the results are discussed below. In sediments of low primary pollen content, the number of pollen grains to approximately 100 Lycopodium spores were counted to provide an indication of pollen concentration in the sample. The results of the initial assessment are presented in Table 1a and 1b, and are expressed as actual pollen counts. The following section headings indicate whether the sample is from Breakwater 1 or 2 and the depth at which the sample was taken.

Breakwater 1 (BW1)

BW1/2-3cm

The pollen spectra from this sample is dominated by tree and shrub pollen, most notably Alnus glutinosa (alder), with a significant representation of Corylus t. (including Myrica gale; bog myrtle and Corylus avellana; hazel), Quercus (oak),



and to a lesser extent Fraxinus (ash), Ulmus (elm), Salix (willow) and Hedera (ivy). Poaceae (grass) and Cyperaceae (sedge) are also well-represented. Other herbaceous pollen is rare with only occasional grains of Filipendula ulmaris (meadowsweet) and Galium (bedstraw) being recorded.

BW1/8-9cm

The pollen sequence in this sample is again dominated by arboreal taxa, comprising over 50 TLP. Alnus declines but remains well-represented, together with Corylus t. and Quercus. Betula (birch) is also recorded. Poaceae comprises a significant percentage of the total land pollen (c. 35 TLP). Other open habitat taxa include Cyperaceae, Galium, Hydrocotyle vulgaris (marsh pennywort), Plantago und. (plantain) and Rumex und. (dock). The aquatic taxon Equisetum (horsetail) is also recorded.

BW1/16-17cm

Arboreal pollen dominates the assemblage, with Alnus values increasing to c. 50 TLP. Quercus, Corylus and Salix are also recorded. Herbaceous pollen taxa are also well represented. Poaceae pollen dominates the herb taxa, comprising c. 35 TLP, and is accompanied by low percentages of Cyperaceae and Galium. Spores of Polypodium (fern) are recorded in low frequencies.

BW1/24-25cm and 32-33cm

These levels remain dominated by arboreal pollen, with Alnus showing a continued increase, attaining c. 70 TLP in 32-33cm. Other tree and shrub pollen are relatively low, including Quercus, Pinus, Ulmus, Corylus, Betula, Salix and Hedera. Herbaceous pollen is dominated by Poaceae (c. 20 TLP) at 24-25cm, together with Cyperaceae (c. 5 TLP). Poaceae declines to c. 5 TLP, whilst Cyperaceae increases slightly to c. 10 TLP at 32-33cm. Aster-type (daisy) pollen is also well represented at 32-33cm, attaining c. 10 TLP.

BW1/48-49cm to 78-79cm

The pollen concentrations in the three samples at the base of BW1 pollen sequence are extremely low and an assessment level pollen count was not achieved in any of the samples. This coincides with the transition to basal blue clay.

Breakwater 2 (BW2)

BW2/6-7cm and 18-19cm

The upper two samples of BW2 are characterised by high arboreal values, dominated by Alnus, which declines from c. 70 TLP at 6-7cm to c. 50 TLP at 18-19cm. Other tree and shrub pollen are well represented, and include Quercus, Corylus t., Ulmus, Tilia (lime), Betula, Pinus, Salix, Hedera and Lonicera (honeysuckle). A variety of herbaceous pollen are recorded, albeit in relatively low percentages, including Poaceae, Cyperaceae, Galium, Hydrocotyle vulgaris, Filipendula, Calluna (ling) and Urtica (nettle).

BW2/30-31cm and 36-37cm

Although dominated by arboreal pollen, most notably Alnus (c. 25 TLP) and Quercus (c. 20 TLP), Poaceae values are also well represented in both samples, comprising c. 30 TLP. Other pollen taxa recorded include Corylus (c. 15 TLP) and Cyperaceae (c. 10 TLP), together with a relatively low representation of Ulmus, Betula, Salix, Plantago and Apiaceae (umbelifs). The aquatic taxon Sparganium erectum (bur-reed) t. is sporadically recorded, along with occasional spores of Sphagnum and Polypodium.



BW2/42-43cm

Poaceae pollen (c. 35 TLP) is dominant, although arboreal pollen still predominates with an increase in the variety of trees represented, most notably Pinus and Betula, both comprising c. 10 TLP. Alnus values remain at approximately 20 TLP, with Quercus and Corylus t. both attaining c. 10 TLP. Other trees and shrubs recorded include Tilia, Ulmus and Salix. Open-habitat taxa recorded in relatively low percentages include Cyperaceae, Artemisia (mugwort), Galium, Aster and Poaceae. Spores of Polypodium are also recorded.

BW2/54-55cm

This level is characterised by a rise in Alnus values to c. 45 TLP. Other tree and shrubs recorded include Quercus, Corylus, Pinus, Betula and to a lesser extent, Ulmus and Salix. A single pollen grain of Juniperus (juniper) and a relatively wide variety of herbaceous taxa are also recorded, including Poaceae, Cyperaceae, Aster, Artemisia, Galium, Caryophyllaceae (pinks) and Chenopodiaceae (goosefoot).

BW2/66-67 and 78-79cm

Pollen concentrations were too low to attain an assessment level count in the basal blue clay.

Interpretation

BW1

It is unfortunate that pollen preservation has prevented the reconstruction of a significant section of the pollen profile. However, some palaeoenvironmental inferences can be made for the upper section. Alder fen woodland appears to have dominated locally, although an increasingly open canopy is reflected by the gradual increase in open-habitat taxa, reaching a maximum at 8-9cm. Cultural indicators, such as Plantago and Rumex are present in low frequencies and may reflect human-induced reduction in the local woodland cover. The upper level (2-3cm) indicates an expansion, once again, in alder fen woodland. Mixed oak woodland persisted in the vicinity throughout.

BW2

The base (54-55cm) of the BW2 pollen sequence reflects a landscape dominated by alder fen woodland locally, with mixed oak woodland within the vicinity of the site. Pinus is present in relatively high percentages at 42-43cm and 54-55cm, which may indicate a local expansion of pine, possibly due to drier ground conditions as a result of falling water levels.

A subsequent decline in tree and shrub pollen is evident at 30-31 and 36-37cm, and although the landscape remained well-wooded, grass-sedge communities were also increasingly prevalent locally. Pollen types indicative of anthropogenic activity are rare, with only Plantago and Apiaceae being recorded. Elm (Ulmus), and to a lesser extent, lime (Tilia), may have formed important components of the surrounding mixed oak woodlands at this time.

The uppermost levels (6-8cm and 18-19cm) of the pollen profile are characterised by re-expansion of alder fen woodland, which may be indicative of increasingly wetter ground conditions or a reduction in human-induced clearance.

Conclusions and recommendations

BW2 provides the most complete pollen profile, although current counting levels and the coarse sampling regime employed may mask significant



vegetational changes. Pollen preservation is generally good above the basal blue clay and the production of a higher resolution pollen diagram, particularly at sedimentary transitions, may reveal a more detailed vegetational succession relating to fluctuations in brackish/freshwater conditions. It may also reveal the wider regional significance of the pollen sequence that is not evident from the assessment. This should be followed by radiocarbon dating of key pollen stratigraphic horizons. Given the significance of the site, and with previous work already carried out in the area, this could provide a useful sequence of vegetation and environmental change in this coastal lowland area.

Acknowledgements

I would like to thank Dr. Roderick Bale for preparing the pollen samples in the palaeoenvironmental laboratories based at the University of Wales, Trinity St David.

References

Andrew, R. (1980): A Practical Guide to Pollen Analysis. Technical Guide 1, Quaternary Research Association, Cambridge.

Jones, J., Tinsley, H. and Brunning, R. (2007): Methodologies for assessment of the state of preservation of pollen and plant macrofossil remains in waterlogged deposits. Environmental Archaeology, 12, 1, pp. 71-86. Association for Environmental Archaeology: Maney.

Moore, P.D., Webb, J.A. & Collinson, M.D. (1991): Pollen Analysis. 2nd edition. Blackwell, Oxford.

Stace C. (1997): A New Flora of the British Isles. Cambridge University Press, Cambridge.

Stockmarr, J. (1971): Tablets with spores used in absolute pollen analysis. Pollen et Spores, 13, pp 615.

Table 1a. Pollen data from Borth BW1, expressed as actual pollen counts.

Borth BW1 2-3cm

BW1 8-9cm

BW1 16-17cm

BW1 24-25cm

BW1 32-33cm

BW1 48-49cm

BW1 72-73cm

BW1 78-79cm

Pollen type

Trees

Alnus 33 18 48 61 67 2 1 2

Betula 2 1 1

Fraxinus 1

Pinus 2 1 1 6

Quercus 10 14 7 7 4 1

Ulmus 2 1 1

Shrubs

Corylus t. 19 19 7 5 6 3

Hedera 1 1

Juniperus

Lonicera

Salix 1 3 1 1



Total Tree & Shrub 67 53 65 78 80 3 2 13

Herbs

Apiaceae

Artemisia 1

Aster 11

Calluna

Caryophyllaceae

Chenopodiaceae

Cyperaceae und. 12 3 1 7 12 1

Filipendula ulmaris 1

Galium 1 4 1 1

Hydrocotyle vulgaris 2 1

Plantago und. 2

Poaceae und. 22 35 35 19 6 1 2

Rumex und. 1

Urtica

Total Herbs 36 47 37 27 30 1 0 4

TLP 103 100 102 105 110 4 2 17

Pteropsida

Equisetum 1

Polypodium 3 6 4 1 Sparganium erectum t.

Sphagnum 1 Pteropsida monolete und. 2 Pteropsida trilete und. Indeterminate grains (Total) 1 8 4 2 7 0 0 9

Degraded 4 2 3

Corroded 1 4 4 5 6

Concealed 2

Lycopodium 14 29 22 20 6 100 100 100

Table 1b. Pollen data from Borth BW2, expressed as actual pollen counts.

Borth BW2 6-7cm

BW2 18-19cm

BW2 30-31cm

BW2 36-37cm

BW2 42-43cm

BW2 54-55cm

BW2 66-67cm

BW2 78-79cm

Pollen type

Trees

Alnus 73 50 25 23 17 46 1 1

Betula 4 2 9 4

Fraxinus

Pinus 1 9 6 1

Quercus 5 14 20 18 11 12

Tilia 2 1

Ulmus 1 4 5 1 1



Shrubs

Corylus t. 12 11 13 14 11 11 3

Hedera 1

Juniperus 1

Lonicera 1

Salix 1 2 3 3 1

Total Tree & Shrub 94 88 63 60 62 82 4 2

Herbs

Apiaceae 1

Artemisia 1 2

Aster 1 3 1

Calluna 1

Caryophyllaceae 1

Chenopodiaceae 2

Cyperaceae und. 1 6 9 12 3 2

Filipendula ulmaris 1

Galium 2 4 3 3

Hydrocotyle vulgaris 1 1

Plantago und. 1

Poaceae und. 12 15 29 29 35 14 3 1

Rosaceae 1

Rumex und.

Urtica 1

Total Herbs 17 28 38 43 44 27 4 1

TLP 111 116 101 103 106 109 8 3

Pteropsida

Equisetum

Polypodium 1 1 1 1 6 5 Sparganium erectum t. 1

Sphagnum 1 Pteropsida monolete undiff. 2 3 1 Pteropsida trilete undiff. 1 Indeterminate grains (Total) 0 1 0 3 6 2 0 0

Degraded 1 2 2

Corroded 3

Concealed 3 1

Lycopodium 6 17 9 51 36 27 100 101



APPENDIX 2:


ASSESSMENT OF SAMPLES FOR TREE RING ANALYSIS AND SPECIES IDENTIFICATION

Nigel Nayling and Roderick Bale: University of Wales, Lampeter

Archaeological Services

Introduction

This report briefly reviews the recovery of samples from trees exposed within the submerged forest horizons on Borth beach which were impacted by Phase 1 of the Borth Coastal Defence Scheme in 2011. These samples have been assessed to define their analysis potential in line with current English Heritage guidance on waterlogged wood and dendrochronology (English Heritage 1998, English Heritage 2010). On the basis of this assessment, recommendations are made for a program of analysis.

Methods

In collaboration with the Dyfed Archaeological Trust, a recommended methodology for the in situ recording and subsequent recovery of trees impacted by the coastal defence scheme were provided as an addition to the existing Written Scheme of Investigation (see below for relevant methodology details). Trees were surveyed using differential GPS by staff from Bam Nuttall, and this data copied to the authors. Trees removed by the developers, were also marked with flags or spray-painted numbers. Samples were taken from some trees prior to their removal, by the authors, whilst other samples were taken from trees recovered and removed to the developer’s compound, or taken from trees placed at the head of the beach after their removal.

Assessment

Survey data provided by the developers has been assessed to ensure its validity. Full mapping has not been produced, but draft scripting through CAD software indicates that the data is usable and in accord with sketch plans produced by the authors during site visits (see attached plan).

Individual samples have been assessed to determine whether they are oak, or require formal microscopic wood identification, and ring counts made of the oak samples to determine if they are suitable for dendrochronological analysis (see table).

Results

A total of 21 samples have been recovered and are available for analysis. Three samples are derived from trees which are non-oak and therefore require microscopic wood identification. The remaining 18 samples are all derived from oak trees including five samples from the largest oak tree recovered (tree 23). Thirteen of these samples have sufficient rings (i.e. over 50) to merit dendrochronological analysis.

Recommendations

The submerged forest exposed on the beach at Borth represents one of the most extensive exposures of known Neolithic date in Britain. Although this exposure has been the subject of previous study in earlier decades, no well replicated tree-ring chronology has been produced, and no absolutely dated tree-ring sequences published (Heyworth 1978, Heyworth 1985). Its attribution to the Neolithic period is based on radiocarbon dates undertaken at a period when dendrochronology was in its infancy in Britain and Ireland. The samples



recovered during the present development therefore provide an opportunity to produce a replicated tree ring width site master which could be cross matched against the long oak chronologies which for Britain and Ireland now extend back to approximately 5200 BC.

Dendrochronological analysis is therefore recommended for the majority of the samples deemed suitable. At least one of the samples from tree 23 should be retained and slow air dried for subsequent polishing to provide an exhibit for local museum display. The remaining samples from this tree should however be subjected to analysis as they were recovered from different locations within the long tree bole recovered, ensuring production of a ring width mean for this tree. Analysis and reporting should follow relevant English Heritage guidelines.

Dendrochronological analysis and selective wood identification of non-oak trees should be contextualised within a report providing mapping of the trees’ location within the peat exposure, including information on tree descriptions collected during site visits and held on individual tree record sheets. Should the resultant ring width data not cross-match against existing tree ring curves from British or Irish prehistoric chronologies, radiocarbon dating of outermost rings from tree 23 (where the outermost sapwood rings survive) is recommended so that the date of this group of trees can be compared with existing radiocarbon dates from the wider submerged forest exposure, and any radiocarbon dates produced from palaeo-environmental samples taken as mitigation for this development.



Sample No.

Tree No.

Flag No.

Sprayed

No.

Sample

Type

Description

Ring

Estimate

Pith

Sapwood

Bark Edge

Dendro

Required

Wood ID

Required

Dim

1

Dim

2

Sample

Date

Assessmen

t Date

1 1 DEND Sample taken during field vis it in advance of development. Located on hand drawn plan. Some very narrow rings 100 1 0 0 1 0 210 125

13/09/11 24/10/11

2 2 DEND Sample taken during field vis it in advance of development. Located on hand drawn plan. 65 0 0 0 1 0 250 185

13/09/11 24/10/11

3 3 DEND Sample taken by RB in advance of development. Located on hand drawn plan. 75 1 0 0 1 0 180 85

26/09/11 24/10/11

4 4 DEND

Sample taken by RB in advance of development. Located on hand drawn

plan. Oak compressed 50 0 0 0 1 0 100 60 26/09/11 24/10/11

5 11 2 DEND Sample taken by RB from pile on beach after excavation by BAM Nuttall 30 0 0 0 0 0 55 55 05/10/11 24/10/11

6 17 DEND Slice sample from flagged tree in pile on beach by RB 120 0 1 1 0 0 190 140 30/09/11 24/10/11

7 17 DEND Slice sample from flagged tree in pile on beach by RB 100 1 0 0 1 0 170 100 30/09/11 24/10/11

8 23 DEND Slice sample from largest tree recovered by BAM Nuttall. Taken on beach by RB 100 0 1 1 1 0 250 130

30/09/11 24/10/11

9 23 DEND Wedge sample taken by RB from largest tree 20 0 0 0 0 0 230 95 30/09/11 24/10/11

10 20 DEND Slice taken by RB 90 1 1 1 1 0 280 250 30/09/11 24/10/11

11 18 ID and COUNT Non-oak slice taken by RB 0 0 1 0 1 240 150

30/09/11 24/10/11

12 14 5 DEND Slice taken in compound from sprayed tree 0 0 0 0 0 180 100 05/10/11 24/10/11

13 3 ID Slice taken in compound from sprayed tree 1 0 1 0 1 130 110 05/10/11 24/10/11

14 14 1 ID and COUNT Slice taken in compound from sprayed tree. Knotty oak 25 1 0 1 0 0 125 100

05/10/11 24/10/11

15 13 4 ID and COUNT Slice taken in compound from sprayed tree. Knotty oak? 0 0 0 0 1

05/10/11 24/10/11

16 8 DEND Slice taken from previously (AH?) sampled oak stump mapped on foreshore but sampled near beach access road after machined removal 70 0 0 0 1 0 370 300

05/10/11 04/11/11

17 7 DEND

Slice taken from previously (AH?) sampled oak bole mapped on foreshore but sampled near beach access road after machined removal (two slices taken 100 1 1 1 1 0 380 370

05/10/11 04/11/11

18 17 DEND Slice (x2) taken by RB after removal by machine from oak bole 120 1 1 1 1 0 330 315 30/09/11 04/11/11

19 23 DEND Largest oak tree encountered. Removed to beach head and samples with chainsaw in two locations 150 1 1 1 1 0 490 430

05/10/11 04/11/11


05/10/11 04/11/11


05/10/11 04/11/11



Methodology used for Dendrochronological sampling

Stage 1 – Initial sand clearance

Assuming that sands are visible within the area of excavation, these should first be removed to the top of surviving tree stumps, peat of clay using a toothless bucket.

If no tree stumps are revealed then the construction work can continue as normal.

Stage 2 – Numbering preserved trees

In the event that a tree stump(s) is revealed, then these should be given a tree number. The tree number sequence should start from 10 to avoid confusion with previously recorded trees in this area (Although this was not

implemented in the end). A list of tree numbers should be kept to ensure duplications are not made.

The tree number will be used as a unique identifier. The number should be fixed to the tree, whether by tag and nail or with spray paint (assuming numbers are kept small). A photograph of the numbered tree should be taken.

Stage 3 – Surveying tree

The tree should then be surveyed as best as is possible, using the tree number as its identification.

Ideally the perimeter of the visible tree should be surveyed using the DGPS that is present on-site. If the ground conditions are too dangerous or unstable for a good survey to be undertaken, a point as close to the centre of the tree would suffice.

Stage 4 – Lifting trees

Following numbering and survey, the tree should be lifted as carefully as possible from the excavation area and placed a safe distance away from the site area.

Care should be taken to avoid unnecessary damage to the wood. Trees should be neatly laid down, and not stacked on top of each other. They should be placed in an area where they will not be affected by machinery and least likely to be disturbed by members of the public.

Stage 5 – Dendrochronology Sampling

When a number of trees have been retrieved, a member of UWLAS will attend the site (either Nigel Nayling or Roderick Bale) to identify the species of trees and establish whether they are suitable for sampling.

Tree record sheets will be completed for the various trees removed.

Trees sampled for dendrochronology and species identification (Nigel Nayling would have to do this if a chain saw was required, as he is a certified user).

Samples to include slices of trees, one of which will subsequently be slow air dried and polished to provide a display item for either the local museum in Borth or Aberystwyth Museum.

Should a slice be placed on display at a museum, UWLAS would undertake to supply associated text and pictures for preparation of a linked display panel which could summarise the results of any dendrochronological analysis and the outcome of other palaeoenvironmental studies.



Bibliography

English Heritage 2010, Waterlogged Wood: Guidelines on the Recording, Sampling, Conservation, and Curation of Waterlogged Wood, 3rd edn, English Heritage.

English Heritage 1998, Dendrochronology: guidelines on producing and interpreting dendrochronological dates, English Heritage London.

Heyworth, A. 1985, Submerged Forests: A Dendrochronological and Palynological Investigation, University of Wales Aberystwyth.

Heyworth, A. 1978, "Submerged forests around the British Isles: their dating and relevance as indicators of post-glacial land and sea level changes" in Dendrochronology in Europe, ed. J. Fletcher,Oxford, pp. 279-288.



BORTH COASTAL DEFENCE SCHEME: PHASE 1,

BORTH, CEREDIGION:


RHIF YR ADRODDIAD / REPORT NUMBER 2012/13

Rhagfyr 2012 December 2012

Paratowyd yr adroddiad hwn gan / This report has been prepared by James Meek Swydd / Position: Head of Field Services Llofnod / Signature ..................................... Dyddiad / Date 13/12/12 Mae’r adroddiad hwn wedi ei gael yn gywir a derbyn sêl bendith This report has been checked and approved by Ken Murphy ar ran Ymddiriedolaeth Archaeolegol Dyfed Cyf. on behalf of Dyfed Archaeological Trust Ltd. Swydd / Position: Trust Director Llofnod / Signature .............…....…… ……....... Dyddiad / Date 13/12/12 Yn unol â’n nôd i roddi gwasanaeth o ansawdd uchel, croesawn unrhyw sylwadau

sydd gennych ar gynnwys neu strwythur yr adroddiad hwn

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BORTH COASTAL DEFENCE SCHEME: PHASE 1, · PDF fileapproximate area of shingle bank ......

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