UNIVERSITY OF GOTHENBURG Department of Earth Sciences Geovetarcentrum/Earth Science Centre

ISSN 1400-3821 B870 Bachelor of Science thesis Gteborg 2015

Mailing address Address Telephone Telefax Geovetarcentrum Geovetarcentrum Geovetarcentrum 031-786 19 56 031-786 19 86 Gteborg University S 405 30 Gteborg Guldhedsgatan 5A S-405 30 Gteborg SWEDEN

Skogaryds geomorfologiska utveckling under sen Weichselian

Basererat p LiDAR-data, jordartskartering (1:3 000) & glaciala erosionsformer

Karina Sundn

2

Sammanfattning Skogaryd r ett forskningsomrde i Vstra Gtaland. Tillgngliga jordartskartor ver omrdet har

upplsningen 1: 50 000. Fr fortsatt forskning i Skogaryd behvs en jordartskarta av hgre upplsning.

Under senaste istiden och dess deglaciation avsattes merparten jordarter som idag prglar landskapet.

Drfr krvs mer information om jordarternas horisontella utbredning i omrdet. Mlet med detta

examensarbete r drmed att utreda isens rrelseriktning under sen Weichselian samt hur senaste

deglaciationen fortgick i Skogaryd.

Fr att n mlet utfrdes en fltstudie i form av: Jordartskartering med hgre upplsning n tidigare (1:3

000), hllanalys samt en analys av klasters trend och plunge i en lagring (fabric analysis). Fltstudien r

utfrd i sammarbete med With (2015).

Resultatet pvisar en isrrelseriktning mot SV (sydvst) i Skogaryd under sen Weichselian. Enligt

analysen av klasters orientering finns tv trender, SO (sydost) och SV. Vidare hade ngra isrfflor en

orientering mot SSV (sydsydvst) ptrffats. Ytterligare underskning mste utfras fr att faststlla

anledningen skillnaden i orienteringarna uppmtta vid fltstudien.

I komplement till fltstudien utfrdes en litteraturunderskning vilken sammanfattningsvis bekrftar att

isen stannat upp en kort period i omrdet, troligen p grund av topografiskillnader. Baserat p datering av

randmorner, vilka avsattes under eller i nrheten korresponderande av HK (hga kustlinjen), pbrjades

avsmltningen fr ca 14 100 r cal BP (kalibrerade r fre nutid) och Skogaryd var helt isfritt ca 500 r

senare. Vidare lg omrdet under HK tills fr ca 11 000 r cal BP, och ligger idag p 80 m .h.

Nyckelord: Skogaryd, Kvartrgeologi, glacialmorfologi, erosionsformer, randmorner, jordartskartering,

fabric analysis, DEM, LiDAR, ArcGIS 10.1, GEOrient

Abstract Skogaryd is a research site in Vstra Gtaland. Available soil maps in the area today have a resolution of

1:50 000. For the continued pursuit of research in the area, an updated soil map with higher resolution is

required. The main part of the soil types in the area was deposited during the last ice age and its

deglaciation. Therefore, more information about the horizontal distribution of soil type in the area is

needed. The goal with this thesis is therefore to determine the ice flow direction during the late

Weichselian and how the latest deglaciation proceeded, in an area of Skogaryd.

This goal will be reached by a creation of a soil map (1:3 000), detection of glacial erosion forms on

bedrock and a fabric analysis. The field study was performed in cooperation with With (2015).

The result shows that the ice had a flow direction towards SW (south west) during late Weichselian.

According to the fabric analysis, clasts were orientated in both SW and SE (south east) direction. A dual

direction on striae also where detected, towards SSW (south south west) and SW. Further investigations

are needed to come to a conclusion what is causing the difference in orientation.

In addition to the fieldwork a literature study was conducted which in conclusion suggests that the ice

stopped a short period in the area, probably due to topography differences. Based on end moraine-dating,

which were deposited beneath or near the the marine limit (HK), the ice started to melt from the area at

14 100 years cal BP (calibrated years before present). Skogaryd was ice free 500 years later. Further on,

the area was positioned below HK during 2000 years, and about 11 000 years cal BP Skogaryd rose above

sea level, and is today situated at 80 m a s l.

Key words: Skogaryd, quaternary geology, glacial morphology, erosional forms, end moraine, soil mapping,

fabric analysis, DEM, LiDAR, ArcGIS 10.1, GEOrient

3

Innehllsfrteckning Abstract ......................................................................................................................................................................................................... 2

1. Introduktion ........................................................................................................................................................................................... 4

1.1 Syfte och ml .................................................................................................................................................................................. 4

1.2 Omrdesbeskrivning .................................................................................................................................................................. 4

1.2.1 Skogaryds antropogena historia .................................................................................................................................. 6

1.2.2 Skogaryds kvartra historia ........................................................................................................................................... 8

2. Metod ......................................................................................................................................................................................................... 9

2.1 Analys av orientering p klaster (fabric analysis) ..................................................................................................... 10

2.2 Jordartskartering ...................................................................................................................................................................... 10

2.3 Glaciala erosions- och landformer .................................................................................................................................... 11

3. Resultat .................................................................................................................................................................................................. 12

3.1 Analys av orientering p klaster (fabric analysis) ..................................................................................................... 12

3.2 Jordartskartering och erosionsformer i Skogaryd ..................................................................................................... 13

3.2.1 Smskaliga erosionsformer ......................................................................................................................................... 16

3.2.2 Medelstora erosionsformer ......................................................................................................................................... 17

3.2.3 Strre strukturer .............................................................................................................................................................. 20

4. Diskussion ............................................................................................................................................................................................ 21

5. Slutsatser .............................................................................................................................................................................................. 24

Tack .............................................................................................................................................................................................................. 24

Referenslista ............................................................................................................................................................................................ 25

Bilaga A SGUs senaste Jordartskartering utfrd av Fredn, 1974. ............................................................................... 27

Bilaga B Jordartskarteringen 1:3 000 ....................................................................................................................................... 28

Bilaga C Jordartskarta 1:3 000 .................................................................................................................................................... 30

4

1. Introduktion

1.1 Syfte och ml Fr fortsatt forskning i Skogaryd behvs en jordartskarta av hgre upplsning fr att ge ett bttre

forskningsunderlag, d smskaliga jordartsfrndringar kan ha stor inverkan p de processer som

studeras i Skogarydsomrdet. Senaste karteringen som denna rapport berr, har enbart en upplsning p

1:50 000 (Fredn, 1974). Fltstudien r utfrd i samarbete med With (2015), vars kandidatuppsats syfte

r studera den vertikala lagringen genom att tolka sedimentloggar, kornstorleksanalyser och

resistivitetsdata frn omrdet.

Syftet med detta examensarbete r att:

Dra slutsatser om isens fldesriktning under sen Weichselian och hur den senaste deglaciationen

fortgick i Skogaryd

Med hjlp av:

- Jordartskartering (1:3 000)

- Glaciala erosionsformer funna i studieomrdet

- Nrliggande randmorner