Surficial Geology of Scott County, Iowa - IIHR · 2014-08-18 · Qaf Qpsb_gla Qptep Qa f Qallt...
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Base map from Iowa DOT Road Map Layers 2009. Iowa Geological and Water Survey digital cartographic file ScottCounty_SurficialGeology.mxd, version 9/28/11 (ArcGIS 10.0) Map projection and coordinate system based on Universal Transverse Mercator (UTM) Zone 15, datum NAD83. The map and cross section are based on interpretations of the best available information at the time of mapping. Map interpretations are not a substitute for detailed site specific studies. Location Map Correlation of Map Units Qtlp Qptep Qal Qali-ht Qaf Qnw2 Qe Qhm Qhmb Qhs Qhsb Qpt Qali-htb Qps Qps1 Qps-gla Qpsb-gla Qps1b-gla Qps2-gla Qgla2 Qgla Qwa3 ! ± Qptlp Qptep Qpsb-gla Qps1b-gla Qhsb Qhs Qhm Qnw Qhmb Qgla Qwa3 Qal Qallt Qnw2 Qpt Qgla2 Qps2_gla Qps1 Qps Qps_gla Prc Dl Dw Sg Ss Om Sh Dc Qe Qali-ht Qaf Qali-htb Wisconsin Pre-Illinois Holocene Pleistocene Hudson Illinois Alluvial and Outwash Deposits Eolian Deposits Glacial Deposits Erosion Surface Sediments Bedrock PENNSYLVANIAN QUATERNARY DEVONIAN SILURIAN ORDOVICIAN A B GEOLOGIC CROSS-SECTION A-B 800 600 500 400 300 200 700 Elevation (feet above sea level) Elevation (feet above sea level) 800 600 500 400 300 200 700 Dodges Creek Buffalo Duck Creek I-80 Hickory Creek West Lake Eldridge Long Grove Qwa3 Qgla Qwa3 Qgla Qgla Qgla Qnw Qallt Qe Qe Qgla2 Qgla2 Qaliht Qnw2 Qal Qwa3 Qal Qptep Qal Qpsb_gla Qpsb_gla Qpsb_gla Qpsb_gla Qps1b_gla Qps1b_gla Qal Qal Qal Prc Prc Prc Dl Dc Dc Dw Dw Sg Sg Sg Ss Sh Om Wapsipinicon River Qali-ht Qnw Qnw SURFICIAL GEOLOGY OF SCOTT COUNTY, IOWA Iowa Geological and Water Survey Open File Map OFM-11-08 September 2011 prepared by Stephanie Tassier-Surine 1 , Deborah Quade 1 , E. Arthur Bettis, III 2 , Robert M. McKay 1 , Huaibao Liu 1 , and James Giglierano 1 Iowa Geological and Water Survey, Iowa City, Iowa Iowa Department of Natural Resources, Roger L. Lande, Director Iowa Geological and Water Survey, Robert D. Libra, State Geologist Supported in part by the U.S. Geological Survey Cooperative Agreement Number G10AC00423 National Cooperative Geologic Mapping Program (STATEMAP) ACKNOWLEDGMENTS Recognized for contributions to map’s production: Andy Asell, Chris Kahle, Ray Anderson, Brian Witzke, Bill Bunker and Mary Pat Heitman. New subsurface geologic data was partly generated by University of Iowa students Sarah Byram and Kyle Bracken who produced descriptive logs of water well drill samples. Jason Vogelgesang and Murray Purdue (IGWS) prepared well samples for stratigraphic logging. Drilling was provided under contract with Aquadrill of Swisher, Iowa, and Cahoy Well & Pump Service, Fredericksburg, Iowa; a special thanks to drilling crew members who worked at times in challenging drilling conditions. Dan Murray, Bob Rowden and Tom Marshall of IGWS provided field assistance during drilling. A special thanks to all landowners who graciously allowed access to their land for drilling: Dean Arp, Bob Dahms, George Goebel, Leonard Hamann, Robert Hamilton, Ellen Kitchen, Don and Karen Krambeck, John Kundell, Kevin Kundell, Steve Marten, Dave Moeller, Dennis and Linda Oberlander, Leroy Paustian, Fred Peeters, Elsie Randolph, William Storjohann, and Kris-Del Farms. Also, thank you to the Iowa Department of Natural Resources for allowing access on public lands for drilling. Thanks to Riverstone Group Inc., Linwood Mining and Minerals Corp., and LaFarge Corporation for access to and information about quarries in the county. Kathy Morris of the Scott County Waste Commission, Basil Nimry of the IDNR Engineering and Realty Services Bureau, Steve Reynolds with the Scott County Secondary Roads Department, and Mitch Tollerud of the Scott County Information Technology Department all provided invaluable boring records from their files. Also, thanks to the Scott County Engineer’s Office for providing access to all of their boring logs for this mapping project. 1 Iowa Geological and Water Survey, Iowa City, Iowa 2 Department of Geoscience, The University of Iowa, 121 Trowbridge Hall, Iowa City, Iowa 52242 Introduction to the Surficial Geology of Scott County, Iowa Scott County lies within a varied and unique surficial geologic region. Geomorphically, it contains the boundary between the Iowan Erosion Surface (IES) to the north and the Southern Iowa Drift Plain to the south (Prior and Kohrt, 2006). Stratigraphically, it contains Illinoian age glacial deposits, which are present only in a small area of southeastern Iowa. Surficial materials consist of a mix of thick eolian deposits (loess), loamy sediments associated with the IES, glacial till outcrop (both Illinoian and Pre-Illinoian), numerous sand and gravel deposits that may be very thick, terraces associated with both the Mississippi and Wapsipinicon rivers and several areas of shallow rock. Multiple periods of Quaternary glaciation and subaerial erosion have led to the landscape we see today. In general, the map area consists of loess and eolian sand of variable thickness overlying Illinoian and Pre- Illinoian glacial sediments. Previous surficial geologic mapping has been completed as part of the STATEMAP program in Scott County (Quade et al., 2004 and 2005; Tassier-Surine et al., 2005, 2009a and 2009b) and to the west in adjacent Cedar County (Quade et al., 2008). The only other regional surficial map of the area consists of the Des Moines 4 o x 6 o Quadrangle at a scale of 1:1,000,000 (Hallberg et al., 1991). Norton (1899) first described and mapped the Quaternary and Paleozoic bedrock geology of the county, and discussed the stratigraphy of the Pennsylvanian, Devonian and Silurian strata that comprise the county’s bedrock units. Statewide bedrock geologic maps by Hershey (1969), and most recently, by Witzke, Anderson, and Pope (2010), depict the increased understanding of the distribution of geologic units at the bedrock surface across this region. At least seven episodes of Pre-Illinoian glaciation occurred in this region between approximately 2.2 and 0.5 million years ago (Boellstorff, 1978a,b; Hallberg, 1980, 1986). Episodic erosion during the last 500,000 years has led to the destruction of pre-existing glacial landforms associated with Pre-Illinoian glaciations. In east-central Iowa, Hallberg formally classified the units into two formations on the basis of differences in clay mineralogy: the Alburnett Formation (several undifferentiated members) and the younger Wolf Creek Formation (including the Winthrop, Aurora and Hickory Hills members). Both formations are composed predominantly of till deposits, but other materials are present. Paleosols are formed in the upper part of these till units. A limited area of southeastern Iowa was glaciated during the Illinois Episode, around 300,000-130,000 years ago. Most of Scott County, with the exception of the area northwest of Mud Creek, was glaciated during this time. Leverett (1898, 1899) was the first to study the Illinoian glacial deposits in southeast Iowa. The Illinoian till was deposited by the advancing Lake Michigan Lobe which moved across western Illinois into Iowa from the northeast (Leverett, 1899; Wickham, 1980). The Lake Michigan Lobe incorporated Paleozoic bedrock materials from the Lake Michigan Basin which are distinguished by both the clay mineralogy of the matrix as well as the pebbles and clasts (Lineback, 1980; Wickham, 1980). Hallberg (1980b) defined the formal stratigraphic nomenclature in Iowa. The only Illinoian Episode till present in Iowa is the Glasford Formation Kellerville Till Member (Willman and Frye, 1970). Following Pre-Illinoian glaciation, most areas of eastern Iowa underwent extensive erosion and landscape development and erosion until the Wisconsin Episode loess began to be deposited. A period of intense cold occurred during the Wisconsin full glacial episode from 21,000 to 16,500 years ago (Bettis, 1989). A periglacial environment prevailed during this period with intensive freeze-thaw action, solifluction, strong winds and a host of other periglacial processes (Walters, 1996). This cold episode and ensuing upland erosion led to the development of the distinctive landform recognized as the IES (Prior, 1976). In eastern Iowa, the highly eroded and dissected Illinoian and Pre-Illinoian upland and older terraces are mantled by Wisconsin loesses of variable thickness (Ruhe, 1969; Prior, 1976). These sediments are the youngest regionally extensive Quaternary materials and were deposited between 30,000 and 12,000 years ago. Two loess units were deposited across eastern Iowa, the older Pisgah Formation and the younger Peoria Fm. The Pisgah is thin and includes loess and related slope sediments that have been altered by colluvial hillslope processes, pedogenic and periglacial processes. The unit is characterized by the presence of a weakly developed soil recognized as the Farmdale Geosol. It is not uncommon to see the Farmdale developed throughout the Pisgah and into the underlying older Sangamon Geosol. Most likely the Pisgah loess was deposited on the eastern Iowa landscape from 30,000 to 24,000 years ago (Bettis, 1989). The Pisgah Formation is typically buried by Peoria Formation loess. The Peoria Formation loess accumulated on stable landsurfaces in eastern Iowa from 25,000 to 21,000 years ago. The Pisgah Formation is in the same stratigraphic position as the Roxanna Silt which is mapped in Illinois. The Peoria Formation consists of silt and sand facies. Esling (1984) undertook a regional study of extensive post Illinoian-age alluvial deposits that had accumulated in major valleys in eastern Iowa. Three major terrace assemblages with differing stratigraphy and age were identified: Early Phase High Terrace (EPHT), Late Phase High Terrace (LPHT) and Low Terrace (LT). EPHT deposits are characterized by the presence of Peoria and Pisgah Formation sediments overlying Sangamon Geosol formed in the underlying alluvium. Esling theorized that these terraces are older than 40,000 years B.P. but younger than the Illinoian sediments in eastern Iowa (Bettis, 1989). LPHT deposits are characterized by the presence of Peoria Formation loess grading down into underlying alluvium with no paleosol. These terraces developed prior to 25,000 years ago and were buried by loess before 12,500 years ago. The LPHT terraces are typically inset into EPHT deposits. The LT is the youngest terrace and is not buried by Peoria loess. Terrace deposits are present primarily along Mud Creek and Duck Creek in the map area. Surficial deposits of Scott County represent of seven formations: DeForest, Noah Creek (~Henry Fm. of Illinois), Peoria, Pisgah (~Roxanna Silt of Illinois), Glasford, Wolf Creek, and Alburnett formations as well as unnamed erosion surface sediments. Hudson-age deposits associated with fine-grained alluvial and colluvial sediments include the DeForest Formation which is subdivided into the Camp Creek, Roberts Creek, Gunder and Corrington members. The Noah Creek Formation includes coarse sand and gravel located along the Wapsipinicon River associated with the development of the Iowan Erosion Surface. Unnamed erosion surface sediments consist of reworked till and slopewash deposits formed by peri-glacial activity during the Wisconsin maximum and may be up to 25’ thick. Peoria Formation eolian materials consist of loess and eolian sand of Peoria Formation materials are present throughout the majority of Scott County except on the area south of the Wapsipinicon River mapped as IES materials. Pisgah Formation loess is also present, being thicker near the Mississippi River and thinning to the west. The characteristics of the eolian deposits vary throughout Scott County. The southeast portion of the county adjacent to the Mississippi River is dominated by thick (up to 60’) loess with almost no eolian sand. An adjacent band comprises the center of the county and is dominated by interbedded silt and fine sand. Areas adjacent to Mud Creek are dominated by loess up to 20’ thick. A buried sand sheet is present in the northwest part of the map area and extends into Cedar County. Illinoian-age deposits are limited to Glasford Formation Kellerville till member References Anderson, W.I., and Garvin, P.L. (eds), 1984: The Cedar Valley Formation (Devonian), Black Hawk and Buchanan counties: Carbonate Facies and Mineralization, area. Geological Society.of Iowa, Guidebook 42, 47 p. Anderson, R.R., and Bunker, B.J. (eds), 1998: Fossil shells, glacial swells, piggy smells, and drainage wells: the geology of the Mason City, Iowa, area. Geological Society.of Iowa, Guidebook 65, 71 p. Belanski, C.H., 1927: The Shellrock Stage of the Devonian. American Midland Naturalist, v. 10, p. 316-370. Bettis, E.A., III, 1989, Late Quaternary history of the Iowa River Valley in the Coralville Lake area in Plocher, O.W., Geologic Reconnaissance of the Coralville Lake area: Geological Society of Iowa Guidebook 51, p. 93-100. Boellstorff, J., 1978a, North American Pleistocene Stages reconsidered in light of probable Pliocene-Pleistocene continental glaciation: Science, v. 202 p. 305-307. Boellstorff, J., 1978b, Chronology of some late Cenozoic deposits from the central United States and the ice ages: Transactions of the Nebraska Academy of Science, v. 6, p. 35-49. Day, J., Luczaj, J., and Anderson, R. (eds), 2006: New perspectives and advances in the understanding of lower and middle Paleozoic epeiric carbonate depositional systems of the Iowa and Illinois basins, In Guidebook for the 36th Annual Field Conference of the Great Lakes Section, Society for Sedimentary Geology (SEPM) and the 67th Annual Tri-State Field Conference, September 29 – October 1, 2006, 167 p. Esling, S.P., 1984, Quaternary stratigraphy of the lower Iowa and Cedar River valleys, southeast Iowa: University of Iowa, Iowa City, unpublished Ph.D Dissertation, 451p. Groves, J.R., Walters, J.C., and Day, J. (eds), 2008: Carbonate platform facies and faunas of the Middle and Upper Devonian Cedar Valley Group and Lime Creek Formation, northern Iowa. IGS Guidebook 28, 96 p. Hallberg, G.R., 1980, Pleistocene stratigraphy in east-central Iowa: Iowa Geological Survey Technical Information Series 10, 168p. Hallberg, G.R., 1986, Pre-Wisconsin glacial stratigraphy of the central plains region in Iowa, Nebraska, Kansas, and Missouri: in Richmond, G.M. and Fullerton, D.S., eds., Quaternary Glaciations in the United States of America, Report of the International Correlation Programme-Project 24: in Sibrava, V., Bowen, D.Q., and Richmond, G.M., (eds.), Quaternary Science Reviews, Quaternary Glaciations in the Northern Hemisphere, v. 5, p. 11-15. Hallberg, G.R., Lineback, J.A., Mickelson, D.M., Knox, J.C., Goebel, J.E., Hobbs, H.C., Whitfield, J.W., Ward, R.A., Boellstorf, J.D., and Swinehart, J.B., 1991, Quaternary geologic map of the Des Moines 4° x 6° quadrangle, United States. U.S. Geological Survey, Miscellaneous Investigations Series, Map I-1420, 1:100,000 scale map sheet. Hershey, H. G., 1969, Geologic map of Iowa, Iowa Geological Survey, scale 1:500,000 (out of print). Koch, D.L., 1970: Stratigraphy of the Upper Devonian Shell Rock Formation of north-central Iowa. IGS Report of Investigations 10, the state of Iowa, 123 p. Leverett, F. 1898. The weathered zone (Yarmouth) between the Illinoian and Kansan Till, Journal of Geology v. 6: 238-243. Leverett, F. 1899. The Illinois glacial lobe: U.S. Geological Survey Monograph, 38, 817p. Lineback, J.A., 1980, The Glasford Formation of western Illinois: Iowa Geological Survey Technical Information Series, no. 11, 181-184. Norton, W. H., 1899, Geology of Scott County: Iowa Geological Survey, Vol. 9, pp. 389-519. Prior, J.C., 1976, Landforms of Iowa: Iowa City, University of Iowa Press, 154 p. Prior, J.C. and Kohrt, C.J., 2006, The Landform Regions of Iowa, Iowa Geological Survey, digital map, available on IDNR GIS Library-ftp://ftp.igsb.uiowa.edu/gis_library/ia_state/geologic/landform/landform_regions.zip; ttp://www.igsb.uiowa.edu/nrgislibx/ Pope, J.P. and Anderson, R. A., 2009, Revision of stratigraphic nomenclature and reclassification of the Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian stages in Iowa, Geological Society of America Abstracts with Programs, v. 41, No. 2, p. 33.Prior, J.C. and Korht, C.J., 2006, The Landform Regions of Iowa, Iowa Geological Survey, digital map, available on IDNR GIS Library- ftp://ftp.igsb.uiowa.edu/gis_library/ia_state/geologic/landform/landform_regions.zip; http://www.igsb.uiowa.edu/nrgislibx/ Quade, D.J., Bettis, E.A. III, and Giglierano, J.D., 2004, Surficial geologic materials of the McCausland Quadrangle, Iowa Geological Survey Open File Map 04-5, 1:24,000 scale map sheet. Quade, D.J., Tassier-Surine, S.A., McKay, R.M., Giglierano, J.D., and Bettis, E.A., III, 2005, Surficial geologic materials of the Eldridge 7.5'' Quadrangle, Scott County, Iowa, Iowa Geological Survey Open File Map 05-5, 1:24,000 scale map sheet. Quade, D.J., Tassier-Surine, S.A., McKay, R.M., Giglierano, J.D. and Bettis, E.A., III, 2008, Surficial Geology of Cedar County, Iowa Final Phase: Surficial Geologic Map of Cedar County, Iowa, Iowa Geological and Water Survey Open File Map 08-8, 1:100,000 scale map sheet. Ruhe, R.V., 1969, Quaternary Landscapes in Iowa: Ames, Iowa State University Press, 255p. Tassier-Surine, S.A., Quade, D.J., Liu, P., Giglierano, J.D., and Bettis, E.A., III, 2005, Surficial geologic materials of the Dixon 7.5'' Quadrangle, Scott County, Iowa, Iowa Geological Survey Open File Map 05-4, 1:24,000 scale map sheet. Tassier-Surine, S., Quade, Deborah, Bettis, E.A., III, McKay, R., Liu, H. and Giglierano, J., 2009a, Surficial Geology of the Davenport West 7.5’ Quadrangle, Scott County, Iowa, Iowa Geological and Water Survey Open File Map 09-6, 1:24,000 scale map sheet. Tassier-Surine, S., Quade, Deborah, Bettis, E.A., III, McKay, R., Liu, H. and Giglierano, J., 2009b, Surficial Geology of the Davenport East 7.5’ Quadrangle, Scott County, Iowa, Iowa Geological and Water Survey Open File Map 09-7, 1:24,000 scale map sheet. Walters, J.C., 1996, General and Environmental Geology of the Cedar Falls/Waterloo Area, The Iowan Surface, in General and Environmental Geology of Cedar Falls/Waterloo and Surrounding Area, Northeast Iowa: Iowa Geological Survey Guidebook Series No. 22, p. 7-9. Wickham, J.T., 1979, Pre-Illinoian till stratigraphy in the Quincy, Illinois area; in the 43 rd annual Tri-State Geological Field Conference, Ilinois State Geological Survey Guidebook 14. Willman, H.B. and Frye, J.C., 1970, Pleistocene stratigraphy of Illinois: Illinois State Geological Survey Bulletin, 94, 204p. Witzke, B.J., Anderson, R.R. and Pope, J.P., 2010, Bedrock Geologic Map of Iowa, scale: 1:500,000, Iowa Geological and Water Survey, Open File Digital Map OFM-10-1. Witzke, B. J., 1994, Silurian Stratigraphy in the Quad Cities Area, Iowa-Illinois, in Paleozoic Stratigraphy of the Quad-Cities Region East-Central Iowa, Northwestern Illinois, Geological Society of Iowa Guidebook 59, p. 3-15. Witzke, B.J. and Bunker, B.J., 1984: Devonian stratigraphy of north-central Iowa. IGS Open File Report 84-2, p. 107-149. Witzke, B.J., Bunker, B.J., and Rogers, F.S., 1988: Eifelian through lower Frasnian stratigraphy and deposition in the Iowa area, central midcontinent, U.S.A. in McMillan, N.J., Embry, A.F, and Glass, D.J. (eds.): Devonian of the World, Canadian Soc. Of Petroleum Geologists, Memoir 14, vol. I, p. 221-250. LEGEND CENOZOIC QUA TERNA RY SY STEM HUDS ON EPIS OD E Qal - Al luvi um (D eForest Fo rmati on -U nd ifferent iat ed) V ariabl e t hi ckn ess of l ess t han 1 to 5 m (3-16 ft) of v ery d ark gra y t o brow n, no ncal careou s to cal careou s, strati fi ed silt y c lay lo am, cl ay loa m, lo am to sand y l oam al lu viu m and co llu viu m in stream va lley s, o n h ill slo pes a nd in clo sed d epression s. Ma y o verli e Gl asfo rd or P re-Ill ino ian forma tio n glac ial til l, Peo ri a Forma tio n l oess o r eoli an sa nd , or N oah Creek Forma tio n 2 san d and grav el. Assoc iate d w it h l ow -reli ef modern fl oo dpl ain , c losed d epressi on s, mod ern d ra ina gewa ys o r to eslop e p osit ion s on t he l an dscap e. Sea sonal h igh w ater ta bl e and p ote ntia l for freq uen t flo od ing . Qall t - Wapsipinico n and Mississippi R ive r V all ey – Low Ter race (DeForest Fo rmat ion -C amp C ree k M br. a nd Rob ert s Creek M br. ). V ariabl e t hi ckn ess of l ess th an 1 to 5 m (3 -1 6 ft ) of v ery da rk gray to b ro wn , n on calca re ous, strati fi ed silt y clay l oam, loa m, or clay l oam, associa ted w ith t he modern ch ann el bel t o f th e Wap si pi nic on Riv er v alle y. O verli es N oah Creek Formati on 2 . Occu pi es lo west po si ti on on the fl oo dpl ain ie. modern chan nel be lts. Sea sona l h igh w ater tab le a nd freq uent floo di ng pot ent ial . Qali -ht - Wapsipinico n and Mi ssi ssi ppi Riv er Val ley – Intermedia te-Hig h Terra ce ( DeForest Fo rmat ion -G un der M br. ). Va ri abl e th ick ness o f less th an 1 t o 5 m (3-1 6 ft ) o f very dark g ra y t o b ro wn , no ncal careou s, sil ty clay lo am to loa ma llu viu m or co llu vi um. O verli es N oah Creek Formati on 2 a lon g t he Wap sipi nic on R iv er or th e He nry Formati on alon g the Missi ssip pi Ri ver. O ccup ies t errace and val ley marg in po siti on 1 t o 2 m (3 -7 ft) ab ove the mode rn fl oo dpl ain . Seaso nal hig h wate r t abl e an d l ow to mo derate fl oo din g p ot enti al. Qali -htb - Mi ssi ssippi R ive r V all ey – Intermedia te-Hig h Terr ace ( D eForest Formati on -G un der Mb r.). V ariab le t hi ckn ess o f l ess t han 1 to 5 m (3-16 ft) of v ery dark gray to brow n, no ncal careou s, silt y clay loa m to loa m allu vi um or c oll uv ium. Ov erl ies D ev oni an C edar V all ey G ro up li mest on e a lon g t he Mississip pi Riv er near B uffal o. Occu pi es terra ce an d vall ey margi n posi tio n 1 to 2 m (3 -7 ft) abo ve th e modern fl oo dpl ain . Seaso nal hi gh wat er t abl e an d l ow to moderat e fl oo din g p ot enti al. Qaf - Al luvi al fa n (Co rrin gto n Mbr.) V ari abl e th ick ness o f 2 t o 5 m (7-16 ft ) of dark brow n t o y ell owi sh b ro wn , n onc alcreou s, sil t l oam t o l oam w ith in terbed ded le nses o f fin e san d an d si lts. A peb bl e lag i s c ommo nl y fo un d a t or n ear th e fan su rface. Ov erl ies thi ck san d a nd g rav el of t he No ah Creek Formati on 2 (alo ng th e Wap sipi nic on Ri ver) o r Hen ry Formati on (alo ng th e Mississi ppi Ri ver). Steep an gled fans o ccur at th e ba se of lo w order drain ag es and col lu vial slo pes al on g t he n orth ern marg in of t he M ississipp i R iv er V all ey. HUDSON AND WISCONSIN EPISODE Qnw2 - Sand and Grav el (N oah Creek Fo rmat ion ) 2 t o 8 m (7-26 ft ) of yel low ish brow n t o g ra y, p oo rl y t o w ell sorted , massiv e to wel l strat ified, coa rse t o fi ne feld spat hic qua rt z sand , p ebb ly sa nd and grav el w ith few int erv eni ng lay ers of silt y clay . A lo ng the Wap sip ini con Ri ver a t hin mant le o f loe ss, re work ed l oess, or fi ne-grain ed allu vi um may be prese nt. Th is un it in clud es sil ty col luv ial dep osit s deriv ed fro m the ad jacen t ma p u ni ts. In pl aces t hi s un it is ma ntl ed wit h 1 to 3 m (3 -1 0 ft ) of fin e t o med iu m, w ell sorted medi um t o fin e san d deriv ed from win d re worki ng o f t he all uv ium. Th is u nit enc ompasses d epo sits t hat accu mu lat ed i n low -reli ef stream val ley s du ri ng the Wi scon si n a nd Hu dson epi sod es. Season al h ig h w ater ta ble . WI SCONS IN EPISOD E Qe - Sand Dunes and Sand She ets (Peo ri a Formati on -sand faci es) Gen erally l ess t han 3 m (10 ft) o f yel low ish bro wn, massiv e, ca lcareou s l oamy sand t o fin e san d. It may ov erl ie yel low ish -b ro wn coa rse-grain ed sa nd and grave l (No ah C re ek Fm. 2 ) o r l oa my Io wa n Erosio n Su rface mat eri als. Usu ally restricte d t o a narro w b elt sou th of th e Wa psip in icon Ri ver Va lley . Qnw - Sand and Grav el (N oah C ree k Fo rmatio n) G enerall y 8 m t o 3 8 m (2 6 t o 1 25 ft) of y ell owi sh b ro wn to gray , p oorly t o w ell sorted , massiv e to w ell stratifie d, c oarse to fin e feld sp ath ic quart z sand , p ebb ly sand an d gravel w ith few in terven ing la yers o f si lty cl ay. Th is u nit i s sho wn on ly in cross sec tio n. It is burie d b y you ng er Hu dso n-a ge al luv ial de posit s asso ciat ed w it h t he Wa psip ini con and Mi ssissipp i R iver v all eys. This u ni t en compa sse s dep osit s tha t ac cumul ated in ri ver v alle ys du ring th e Wiscon sin Episo de. Qhm - Outwash Sa nd and Pebbl y Sand (Hen ry Formati on , M uscat ine Mb r. ) coa rse to fin e san d an d peb bly san d mant led w ith u p to 1 .5 m (5 ft) o f eol ian san d; K in gsto n T errace co mp lex i n th e Mi ssi ssi pp i V alle y. Qhmb - Outw ash Sand and Pe bbly Sand Sha llo w to Bedrock (Hen ry Formati on, Mu sca tin e Mb r. ) c oarse to fine sand and pe bbl y san d man tl ed w ith u p to 1. 5 m (5 ft) o f eoli an sa nd; Ki ng ston Terrac e comp lex in t he M ississip pi Val ley . Ov erl ies Si luria n G ow er Format io n fo ssil iferou s dol omit es o f the An amosa and LeCl aire M emb ers fro m th e n ort hern part of t he quad t o n orth o f B ett end orf. Fro m Bet ten dorf area sou th, th e d eposi t i s ben ched o n Mi ddl e D evo nia n Wapsi pin ico n G ro up do lomi te a nd l imesto ne a nd or Low er Pennsy lva nia n Ra ccoo n C reek Grou p sh ale, mud st on e or san dsto ne. Qhs - Outwash Sand and Pebbly Sand (H enry Fo rmati on , Sabu la Mbr.) co arse to fi ne sa nd and pe bbl y san d ma ntl ed wit h u p t o 5 m (16 ft) of eo lia n san d; Sa van na Terrace compl ex i n t he Missi ssi ppi Va lley . Qhsb - Outwa sh Sa nd and Pebbly Sand Shallo w to Bedroc k (H enry Forma tio n, Sa bu la Mbr.) co arse t o fi ne sa nd an d peb bly san d ma ntl ed wi th u p t o 5 m (16 ft) o f eol ian san d; Savan na Ter rac e comp lex in t he Mississip pi Va lle y. Ov erl ies Sil urian G ow er Format io n fossi liferous do lomit es o f th e A namosa and LeC laire Members from t he north ern p art o f th e q uad to n orth of B ette ndo rf. Fro m Bet ten dorf area sou th, th e d eposi t i s ben ched o n Mi ddl e D evo nia n Wapsi pin ico n G ro up do lomi te a nd l imesto ne a nd or Low er Pennsy lva nia n Ra ccoo n C reek Grou p sh ale, mud st on e or san dsto ne. Qpt - Lo ess Mantl ed Ter race (Peo ria Forma tio n – silt an d/o r sand facies) 2 to 7 m (7-23 ft ) of y ello wi sh b ro wn to gray , massiv e, j oin ted , ca lcareou s or n on calca reo us, si lt loa m and in tercal ated fine to medi um, w ell sorte d, sa nd. May g ra de d ow nw ard t o p oo rl y t o mo deratel y wel l so rt ed, mod erat ely to w ell strati fi ed, coarse t o fi ne fel dspat hi c qu artz sand, l oam, o r silt lo am al luv iu m (Lat e Pha se H igh Terrac e) or may o verlie a Farmdale G eo so l d evel oped in Pisg ah Silt wh ich i n tu rn overli es a wel l-expressed San gamo n Geo sol d evel op ed in poo rly to mo derate ly w ell so rt ed, mod era tel y to w ell strati fi ed, coarse t o fin e sand , lo am, o r si lt loam al lu viu m (Ea rly Phase Hig h Terrace). Th e Pisg ah Formati on is in t he same st rat igrap hic po si ti on a s th e Ro xan na Sil t w hic h i s ma ppe d i n Illi no is. Qptlp - La te Phase High Terr ace (LPHT ) (Peo ria Formati on -sil t and /o r sand faci es) 2 to 7 m (7 -2 3 ft) o f yel lo wish b ro wn t o gray , massiv e, jo int ed, ca lcareou s o r n onca lcareou s, si lt l oam and in tercala ted fi ne t o med ium, wel l sort ed, san d. Grade s do wnw ard t o p oorly to mod erat ely wel l so rt ed, moderat ely to wel l strati fi ed, coarse t o fin e feld sp ath ic quartz sand , lo am, o r sil t l oam al lu viu m. Qptep - Earl y Pha se Hig h Te rrac e (EPHT) (Peo ri a Formati on -sil t and /or sand facie s) 2 t o 7 m (7-23 ft) o f yel lo wish b ro wn t o gray, massiv e, j oi nted , calca reo us or n on calcareo us, silt l oam a nd in tercala ted fi ne t o me diu m, we ll so rt ed, sand . Th e Peoria dep osit s ov erl ie a Farmda le G eo so l deve lop ed in the Pisgah Forma tio n whi ch i n turn ove rl ies a wel l-exp ressed Sang amon Geo sol dev elo ped in po orly to mod era tely w ell sorted , mo deratel y t o wel l st rat ifi ed, co arse to fi ne sa nd , l oam, o r silt lo am al luv iu m. Th e Pisga h Fo rmati on is in th e same st rat igrap hic po siti on as t he R ox ann a Silt w hi ch i s mapp ed i n Ill ino is. Qps - Loess (Peoria Fo rmat io n—silt fa cies) Gen era lly 2 to 8 m ( 7 -2 6 ft) o f yel lo wish to gray ish brow n, ma ssi ve, jo int ed calcareo us o r no ncal car eou s silt lo am t o si lty cla y loam. O verlie s a g ra yish brow n to ol iv e g ra y si lty cl ay lo am to si lty cl ay (Pi sg ah Fo rmat io n—erod ed Farmdal e G eoso l) w hic h is l ess th an 1.5 m (5 ft) t hi ck. T he Pi sg ah Format io n is i n the same st rat igrap hic p osit ion as th e Ro xan na Si lt wh ich i s mapp ed in Illi no is. Th e Farmd ale G eosol ap pears to be di st urbed by perig laci al acti on an d is wel ded to an o ld er Sa nga mo n Geo sol de vel ope d i n loa my g laci al til l of t he Wo lf Creek or Al bu rn ett fo rmati on s. Thi s mapp ing un it enco mpasses u plan d div ide s, ri dg eto ps an d co nv ex si deslo pe s. Well to somewh at p oo rl y d rai ned lan dscap e. Qps1 - Lo ess and Interc ala ted E ol ian Sand (Pe oria Formati on -sil t faci es) 2 to 10 m (7 -3 3 ft ) of yel lo wish bro wn to gray, massive , fra ctured , no nca lcareou s grad in g d ow nwa rd to cal careou s silt lo am and i nte rcal ate d fin e t o me diu m, w ell sorted , sa nd. Sand i s most abu nd ant in l ow er part of t he eol ian pa ckag e- eol ian d un es 0. 5 t o 2.5 m (2 -8 ft) t hick may b e p resen t at the ba se o f thi s un it . O verli es massive , fract ured, loa my g lacia l ti ll of th e Wol f C reek or A lbu rnett format io ns w ith or w ith ou t in terve nin g c laye y Farmd ale /Sang amon Geo sol. Qps-gl a - Lo ess (Peoria Formatio n—sil t fa cies) Ge nerall y 2 to 8 m (7 -2 6 ft ) of yell ow ish to gra yi sh b ro wn , massi ve, jo in ted cal careou s o r no nca lcareou s sil t lo am t o si lt y clay l oam. O verli es a grayi sh brow n t o o liv e g ra y sil ty cla y l oam t o si lty cla y (Pisga h Formati on - ero ded Fa rmda le G eo so l) w hich i s less t han 1. 5 m (5 ft ) th ick. Th e Pisga h Formati on is i n the same strati graph ic po si tio n a s th e R ox anna Sil t wh ich i s map ped in Ill in ois. The Fa rmda le Ge osol ap pea rs to be d istu rb ed by perigl acia l a cti on an d is wel ded t o a n ol der San gamon G eoso l dev elo ped i n loa my g laci al ti ll o f th e Gl asfo rd Forma tio n. Thi s ma ppi ng un it e nco mp asses up lan d d ivi des, ri dg etop s an d co nv ex si deslo pes. Wel l t o so me wha t p oorl y drai ned lan dscap e. Qpsb-g la - Thick Loe ss (Peoria Formati on - sil t fac ies) G enerall y 5 to 15 m (1 6-49 ft) of yel low ish to grayi sh brow n, massiv e, joi nt ed calc are ou s o r no ncal careou s sil t lo am t o silt y cla y lo am. Ov erlie s ma ssi ve, frac tured, cla y loa m gla cial ti ll of t he Gla sfo rd Forma tio n wit h or w ith ou t i nte rv eni ng cla yey Farmda le Geo sol and Pisga h Fo rmati on materia ls. T he Pi sg ah Format io n i s in t he sa me strati gra ph ic p osit ion as t he R oxa nna Silt wh ich is map ped in Il lin oi s. Thi s ma ppi ng un it enco mp asses up lan d d iv ide s, ri dg eto ps an d co nv ex si desl ope s. Well t o so mewh at p oo rl y d rai ned lan dscap e. Qps1 b-gl a -T hic k Lo ess a nd I nterca lated E oli an Sa nd (Peoria Formati on-sil t faci es) 5 to 1 5 m (16 -4 9 ft) of y ell owi sh brow n to gray , massiv e, no ncal careou s g rad in g dow nw ard t o cal care ous silt lo am an d int ercalat ed fi ne to medi um, wel l so rt ed, san d. Mi ni mu m th ick ness of 5 m (1 6 ft) on up lan ds. Maxi mum t hick ne ss of 2 -7 m (7 -2 3 ft ) of l oess o ccu rs on adj acen t sl op es. O verlie s massi ve, fract ured, lo amy g lacia l ti ll of th e Illi no ian Gla sfo rd Format io n w ith or w ith ou t i nterv enin g clay ey Farmdale /San gamon Geo sol . Qps2 _g la - Eoli an Sa nd a nd Inte rcal ated Si lt (Peoria Fo rmati on —sa nd fa cies) G eneral ly fi ve t o fi ft een met ers (1 6 to 49 feet) o f yell ow ish brow n t o gra y, mo derat ely to wel l st rat ified no ncal careou s or calca reo us, fin e t o medi um, wel l sorted , eol ian san d. Ma y con tai n int erbed s o f y ello wi sh brow n to g ra y, massive, si lt lo am loe ss. O verlie s massiv e, fract ured, l oamy g lacia l til l of th e Ill ino ian Gl asfo rd Forma tio n w it h o r wit hou t i nt erv eni ng clay ey Farmdal e /San gamon Ge osol . Qgl a2 - Loa my and Sandy Sediment Sha llo w to Gla cia l T ill (Un named erosio n surfac e sed iment ) 1 t o 3 m (3 -1 0 ft) o f ye llo wi sh bro wn to gray , massi ve t o weak ly strati fi ed, wel l to po orly sorted lo amy, sand y and si lt y ero sion su rfac e sed iment . Map u nit incl ud es so me a reas mant led w it h less tha n 2 m (7 ft) o f Peoria sil t or san d. O verli es massiv e, fract ured, firm g laci al ti ll o f th e Ill ino ian Gl asfo rd Forma tio n. Sea so nal ly hi gh wat er tabl e may occu r in thi s ma p u ni t. ILLI NOIS EPIS OD E Qgl a - T ill (G lasford Fo rmat ion ) Ge nerall y 3 t o 10 m (10 -3 3 ft) of very den se, massiv e, fractu red, loa my g laci al til l of th e Ill in oian G lasford Forma tio n wit h or w ith out a th in lo ess mant le (Peo ri a Format io n—less than 2 m) and in terven in g cl ay ey Farmdal e/Sang amon Ge osol . Upp ermo st t ill may be rew orke d (associ ated w ith th e Iow an Su rface). Drai nag e is variab le from w ell drai ned to po orly drain ed. PRE-ILL INOIS EPIS OD E Qwa3 - T ill (Wolf C reek o r Al burn ett fo rmat ion s) G eneral ly 10 to 3 5 m (3 3-11 5 ft) o f ve ry de nse, ma ssi ve, fract ured, lo amy g laci al til l o f th e Wol f Creek o r Al burne tt fo rmati on s w ith or wit hou t a th in lo ess mantl e (Peor ia Fo rmat ion —less t han 2 m) a nd int erven ing cl ayey Farmd ale/ Sa nga mo n G eo so l. Thi s ma ppi ng un it enc ompasses n arro wl y d issecte d i nt erflu ves a nd si de slop es, a nd side val ley slo pes. Drain age is va ria bl e fro mw ell drain ed to po orl y dra ine d. PALEOZOIC PALEOZOIC ERATHEM PENN SY LVAN IAN S YS TEM Prc - R AC COON CR EEK GROU P (primarily Mo rrow an; lo call y i ncl ud es At ok an-lo wer D esmo in esian Tra dew ater Formatio n in up per pa rt ). Reco gn ized on ly in eastern Iowa in Scot t an d Muscat in e cou nt ies; in clu des i n a scend in g o rd er th e “ Caseyv ill e” and Tradew ater formati on s. Rest s un con fo rmab ly on o lder ma p u ni ts i n t he cou nt y an d fi ll s pal eova ll eys a nd pal eok arst d evel ope d i n und erlyi ng Silu ri an and D evo nia n carb on ate ro cks. Pri ma ry li th olo gie s are: shale /mud st on e, l ig ht to da rk g ray , partly sil ty t o san dy ; sa ndst one , v ery fin e t o me diu m grain ed; si ltsto ne, gray . Seco nd ary l ith ol ogi es are: ca rb ona ceou s sha le/mu dsto ne, gray t o black ; pho spha tic bla ck sh ale; li mest on e, d ense, partl y fossil iferous, partl y san dy ; co al (b eds l ocal ly > 2 ft). M ino r lit ho log ies a re: sand sto ne, coarse grai ned to granu lar, partly co ngl omerati c; mu dsto ne, red t o p ink ; l imesto ne con cret io ns (may b e sep tarian ); co ne-in -co ne l imesto ne; sid eri te/ iro nst one con cretio ns and pel let s; py ri tic . Ma ximu m thi ckn esses: 1 95 ft (59 m). D EV ONIAN SYSTEM Dl - LIME CR EEK FOR MA TION (Up per D evo nian , u pp er Frasni an). Th e format io n i s comprise d en tirely o f t he Sw eetl and Creek Sh ale i n the sout hw est p ortio n o f the cou nt y. Primary li th olo gi es are li ght green to bro wn sh ale, and green silt sto ne c ont aini ng an abu nda nt and di verse fossil con od ont fauna . Ma ximu mt hi ckn ess to 12 ft (4 m). Dc – CED AR V AL LEY GR OU P (Mi dd le-Up per Dev oni an, mi ddl e Giv eti an-lo wer Frasni an). The g ro up i nclu des in ascend in g order the Li ttl e Cedar, Co ra lvi lle, a nd Lit ho graph C ity fo rmati on s. Pri mary lit ho log ies a re: fossili ferou s li me st on e, w ith an abu nd ant and di verse in verte bra te fau na, variab ly arg ill aceo us, p ar tly bi ostromal ; an d d ol omit e, pa rt ly fo ssi l-mo ld ic t o v ug gy, variab ly argil lac eous. Max imum th ick ness o f 8 5-90 ft (26 -2 7 m) occu rs in the sout hw est p orti on of th e cou nt y n ear Bu ffalo . D w - WA PSIPINIC ON GR OU P (Mi ddl e D evo ni an, up per Eifel ian-mid dle Gi vet ian). The group i nclu de s in ascen di ng order t he B ert ra m, O tis, and Pini con Ri dg e forma tio ns. Primary lit ho log ies a re: do lo mi te, p art ly lamin ated , variab ly arg ill aceo us, pa rt fet id; and limesto ne, den se, “sub lit ho gra ph ic”, p artly lamina ted to i ntracl astic; do lo mi te, fossil -mol di c to vug gy (lo wer O tis fm). Seco nda ry li tho lo gie s are: l imesto ne/ dol omit e b recc ia (ev apo ri te coll apse, up per Pin ico n R id ge Fm); d ol omiti c sha le and shal y dol omit e, gra y t o green-gray, p art ly silt y-sand y; li mest one , p art ly pe loi dal -o oli tic to fossili ferou s (Ot is Fm). Min or l ith olo gi es are: chert a nd chal cedo ny n odu les (Pin ico n Ri dg e Fm); and san dsto ne, fi ne to mediu m wi th larger d ol omite cla st s (B ertra m Fm). Ma xi mu m thi ckn esses o f 1 12 ft (34 m). SILURIAN S YSTEM Sg - GOWER FORMAT ION (Low er-?U ppe r Si lurian , Wen loc k-?Lud low ). The format io n i ncl ud es A namosa and LeCl aire memb ers; LeCl aire M ember ca n b e a fo ssili ferou s carb ona te mo und faci es or a ho ri zon tall y stra tified fossil -mo ldi c facie s. Erosio nal ly bev eled an d t ru nca ted be neat h D w. Pri mary li tho lo gie s are: l amina ted to stromato li tic do lo mit e (A namosa Mbr), pa rt feti d/o rg ani c; dol omit e mud st on e, d en se, featu reless. Se con dary lit hol og ies a re: d ol omite, fossil ifero us to vu gg y, mo ld ic,; d olo mi te, pa rt ly coa rsel y cry stall in e, v ug gy, fossil ifero us to sparsely fossil ifero us, part crino id al and coral lin e (LeClai re Mbr). Mi no r l ith ol ogi es are: cher t; in tra clasti c d olo mi te. Max imum th ick ness o ccurs at LeCla ire, 1 50 ft (4 6 m); t hi ns to th e sou th west to 70 ft (2 1 m) at Blu e G rass. Ss - SCOTC H GROV E FOR MA TION (Lo wer Sil urian , u pp er Lla ndo very-lo wer Wen lock ). Th e formati on in clu des th e Joh ns Creek Qu arry, Welt on , B uck Creek Q uarry , Wau beek , and Pali sa des- Ke pler memb ers. Th e b ulk of t he fo rmat ion i s co mprised o f the fin ely fossil -mol di c Welt on Me mb er. Ca rb ona te moun d fa cies of t he Palisa des-Kep ler M ember are repla ced lat era lly b y in ter -mou nd strata o f th e Wau beek M ember. Everyw here ov erl ain b y Sg. Pri maril y lit ho lo gies are: do lo mi te, p orous, fossil -mol di c t o vu gg y, part v ery cri noi dal (in clu des Wel to n Mbr); dol omit e, cherty t o very che rt y, d ense (B uck C re ek Qu arry Mbr). Seco nda ry lit hol og ies are: do lo mi te, spa rsel y fossil-mol dic, d en se, p art vu ggy (i ncl ude s Waub eek M br); d ol omit e, coarsely cry stall in e, part v ery cri noi dal (wit hin Joh ns Creek Qu arry and Pa lisad es-K epl er mb rs); dol omite mu dst one , de nse. Mi no r l it hol ogi es are: d ol omite, slig ht ly a rg ill aceo us; q uartz druse, c halc edo ny, sili cified fo ssils. Maxi mu m th ick nesses o f 1 50 ft (46 m). Sh – HOPKIN TON AND BL AN DIN G fo rmatio ns (Low er Silu ri an, ?Rhu dd ani an, Aeron ian -u pp er Ll and ov ery . Th e Bl and ing Forma tio n marks t he base o f the Silu ri an i n t he cou nty an d i s ov erl ain by th e sub stan tial ly th ick er H o pki nto n Fo rmati on . The map uni t i s at the bed ro ck su rface on ly wi thi n t he d eep ly buri ed b edrock va lle y (Cle ona Cha nn el) in th e no rt hern and we st ern p art of c oun ty. Pri mary li tho lo gie s are: d olo mi te, fossil -mol di c t o vu gg y, fine t o coarse crystal lin e; do lo mi te, d ense to p orou s, c herty t o very ch ert y, n odu lar to be dd ed che rt (espec iall y Bla ndi ng Fm). M axi mu m map -u nit th ick nesses o f 1 10 ft (35 m); Ho pki nt on 9 5 ft (3 0 m); B land in g 1 5 ft (5 m). This u ni t i s sh ow n o nl y i n t he cro ss se ctio n. ORDOVICIAN SYSTEM Om - MA QU OKET A FOR MATION (Upp er O rd ovi cia n; Ric hmon dian [u pper Kat ian ]). T he fo rmati on i nclu des in asce ndi ng ord er th e El gin , Clermont , Fo rt A tki nson , and Brai nard me mb ers. Th e map un it is at the be drock surfa ce onl y wit hi n the de eply b uried b edrock v all ey (C leon a C han nel ) in th e n orth ern p art o f cou nt y. Pri mary li tho lo gies are: shale , g re en-gray, varia bly d ol omiti c, mo stly un fo ssi li ferou s; d ol omite , argi lla ceou s, p art ly shal y, variab ly fo ssili ferou s; dol omit e, p art ly argil lace ous, partl y c herty . Seco nda ry li tho lo gie s are: sh ale, brow n to brow n-gray, organ ic, pa rtl y grapt oli tic, partl y fi nely la mi nat ed (lo wer st rat a); in terbed ded d olo mi te a nd shal e, p art ly fo ssili ferou s. Mi no r lit hol og ies are: do lomi te, pho spha tic, argil lac eous (El gin Mb r.). Max imum th ick nesses o f 21 0 ft (64 m). Thi s un it i s sho wn onl y in the cro ss secti on. Qf – Fil l Areas o f maj or lan d fil lin g. Fi ll associa ted wi th rai lroad grade s, hi gw ay g ra des, a nd land l evel ing . V ariabl e t extu re. Dr ill Holes to Bedroc k Water Wel l R ecor ds Qf
Transcript of Surficial Geology of Scott County, Iowa - IIHR · 2014-08-18 · Qaf Qpsb_gla Qptep Qa f Qallt...
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Surficial Geology of Scott County, Iowa
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Base map from Iowa DOT Road Map Layers 2009. Iowa Geological and Water Survey digital cartographic file ScottCounty_SurficialGeology.mxd, version 9/28/11 (ArcGIS 10.0)
Map projection and coordinate system based on Universal Transverse Mercator (UTM) Zone 15, datum NAD83.The map and cross section are based on interpretations of the best available information at the time of
mapping. Map interpretations are not a substitute for detailed site specific studies.
Location Map
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Title, Author, Agency, Contract and Acknowledgement Information
SURFICIAL GEOLOGY OF SCOTT COUNTY, IOWA
Iowa Geological and Water Survey
Open File Map OFM-11-08 September 2011
prepared by
Stephanie Tassier-Surine1, Deborah Quade1, E. Arthur Bettis, III2, Robert M. McKay1, Huaibao Liu1, and
James Giglierano1
Iowa Geological and Water Survey, Iowa City, Iowa
Iowa Department of Natural Resources, Roger L. Lande, Director Iowa Geological and Water Survey, Robert D. Libra, State Geologist
Supported in part by the U.S. Geological Survey Cooperative Agreement Number G10AC00423
National Cooperative Geologic Mapping Program (STATEMAP)
ACKNOWLEDGMENTS Recognized for contributions to map’s production: Andy Asell, Chris Kahle, Ray Anderson, Brian Witzke, Bill Bunker and Mary Pat Heitman. New subsurface geologic data was partly generated by University of Iowa students Sarah Byram and Kyle Bracken who produced descriptive logs of water well drill samples. Jason Vogelgesang and Murray Purdue (IGWS) prepared well samples for stratigraphic logging. Drilling was provided under contract with Aquadrill of Swisher, Iowa, and Cahoy Well & Pump Service, Fredericksburg, Iowa; a special thanks to drilling crew members who worked at times in challenging drilling conditions. Dan Murray, Bob Rowden and Tom Marshall of IGWS provided field assistance during drilling. A special thanks to all landowners who graciously allowed access to their land for drilling: Dean Arp, Bob Dahms, George Goebel, Leonard Hamann, Robert Hamilton, Ellen Kitchen, Don and Karen Krambeck, John Kundell, Kevin Kundell, Steve Marten, Dave Moeller, Dennis and Linda Oberlander, Leroy Paustian, Fred Peeters, Elsie Randolph, William Storjohann, and Kris-Del Farms. Also, thank you to the Iowa Department of Natural Resources for allowing access on public lands for drilling. Thanks to Riverstone Group Inc., Linwood Mining and Minerals Corp., and LaFarge Corporation for access to and information about quarries in the county. Kathy Morris of the Scott County Waste Commission, Basil Nimry of the IDNR Engineering and Realty Services Bureau, Steve Reynolds with the Scott County Secondary Roads Department, and Mitch Tollerud of the Scott County Information Technology Department all provided invaluable boring records from their files. Also, thanks to the Scott County Engineer’s Office for providing access to all of their boring logs for this mapping project. 1Iowa Geological and Water Survey, Iowa City, Iowa 2Department of Geoscience, The University of Iowa, 121 Trowbridge Hall, Iowa City, Iowa 52242
Introduction to the Surficial Geology of Scott County, Iowa
Scott County lies within a varied and unique surficial geologic region. Geomorphically, it contains the boundary between the Iowan Erosion Surface (IES) to the north and the Southern Iowa Drift Plain to the south (Prior and Kohrt, 2006). Stratigraphically, it contains Illinoian age glacial deposits, which are present only in a small area of southeastern Iowa. Surficial materials consist of a mix of thick eolian deposits (loess), loamy sediments associated with the IES, glacial till outcrop (both Illinoian and Pre-Illinoian), numerous sand and gravel deposits that may be very thick, terraces associated with both the Mississippi and Wapsipinicon rivers and several areas of shallow rock. Multiple periods of Quaternary glaciation and subaerial erosion have led to the landscape we see today. In general, the map area consists of loess and eolian sand of variable thickness overlying Illinoian and Pre-Illinoian glacial sediments.
Previous surficial geologic mapping has been completed as part of the STATEMAP program in Scott County (Quade et al., 2004 and 2005; Tassier-Surine et al. , 2005, 2009a and 2009b) and to the west in adjacent Cedar County (Quade et al., 2008). The only other regional surficial map of the area consists of the Des Moines 4 o x 6 o Quadrangle at a scale of 1:1,000,000 (Hallberg et al., 1991). Norton (1899) first described and mapped the Quaternary and Paleozoic bedrock geology of the county, and discussed the stratigraphy of the Pennsylvanian, Devonian and Silurian strata that comprise the county’s bedrock units. Statewide bedrock geologic maps by Hershey (1969), and most recently, by Witzke, Anderson, and Pope (2010), depict the increased understanding of the distribution of geologic units at the bedrock surface across this region.
At least seven episodes of Pre-Illinoian glaciation occurred in this region between approximately 2.2 and 0.5 million years ago (Boellstorff, 1978a,b; Hallberg, 1980, 1986). Episodic erosion during the last 500,000 years has led to the destruction of pre-existing glacial landforms associated with Pre-Illinoian glaciations. In east-central Iowa, Hallberg formally classified the units into two formations on the basis of differences in clay mineralogy: the Alburnett Formation (several undifferentiated members) and the younger Wolf Creek Formation (including the Winthrop, Aurora and Hickory Hills members). Both formations are composed predominantly of till deposits, but other materials are present. Paleosols are formed in the upper part of these till units.
A limited area of southeastern Iowa was glaciated during the Illinois Episode, around 300,000-130,000 years ago. Most of Scott County, with the exception of the area northwest of Mud Creek, was glaciated during this time. Leverett (1898, 1899) was the first to study the Illinoian glacial deposits in southeast Iowa. The Illinoian till was deposited by the advancing Lake Michigan Lobe which moved across western Illinois into Iowa from the northeast (Leverett, 1899; Wickham, 1980). The Lake Michigan Lobe incorporated Paleozoic bedrock materials from the Lake Michigan Basin which are distinguished by both the clay mineralogy of the matrix as well as the pebbles and clasts (Lineback, 1980; Wickham, 1980). Hallberg (1980b) defined the formal stratigraphic nomenclature in Iowa. The only Illinoian Episode till present in Iowa is the Glasford Formation Kellerville Till Member (Willman and Frye, 1970).
Following Pre-Illinoian glaciation, most areas of eastern Iowa underwent extensive erosion and landscape development and erosion until the Wisconsin Episode loess began to be deposited. A period of intense cold occurred during the Wisconsin full glacial episode from 21,000 to 16,500 years ago (Bettis, 1989). A periglacial environment prevailed during this period with intensive freeze-thaw action, solifluction, strong winds and a host of other periglacial processes (Walters, 1996). This cold episode and ensuing upland erosion led to the development of the distinctive landform recognized as the IES (Prior, 1976).
In eastern Iowa, the highly eroded and dissected Illinoian and Pre-Illinoian upland and older terraces are mantled by Wisconsin loesses of variable thickness (Ruhe, 1969; Prior, 1976). These sediments are the youngest regionally extensive Quaternary materials and were deposited between 30,000 and 12,000 years ago. Two loess units were deposited across eastern Iowa, the older Pisgah Formation and the younger Peoria Fm. The Pisgah is thin and includes loess and related slope sediments that have been altered by colluvial hillslope processes, pedogenic and periglacial processes. The unit is characterized by the presence of a weakly developed soil recognized as the Farmdale Geosol. It is not uncommon to see the Farmdale developed throughout the Pisgah and into the underlying older Sangamon Geosol. Most likely the Pisgah loess was deposited on the eastern Iowa landscape from 30,000 to 24,000 years ago (Bettis, 1989). The Pisgah Formation is typically buried by Peoria Formation loess. The Peoria Formation loess accumulated on stable landsurfaces in eastern Iowa from 25,000 to 21,000 years ago. The Pisgah Formation is in the same stratigraphic position as the Roxanna Silt which is mapped in Illinois. The Peoria Formation consists of silt and sand facies.
Esling (1984) undertook a regional study of extensive post Illinoian-age alluvial deposits that had accumulated in major valleys in eastern Iowa. Three major terrace assemblages with differing stratigraphy and age were identified: Early Phase High Terrace (EPHT), Late Phase High Terrace (LPHT) and Low Terrace (LT). EPHT deposits are characterized by the presence of Peoria and Pisgah Formation sediments overlying Sangamon Geosol formed in the underlying alluvium. Esling theorized that these terraces are older than 40,000 years B.P. but younger than the Illinoian sediments in eastern Iowa (Bettis, 1989). LPHT deposits are characterized by the presence of Peoria Formation loess grading down into underlying alluvium with no paleosol. These terraces developed prior to 25,000 years ago and were buried by loess before 12,500 years ago. The LPHT terraces are typically inset into EPHT deposits. The LT is the youngest terrace and is not buried by Peoria loess. Terrace deposits are present primarily along Mud Creek and Duck Creek in the map area.
Surficial deposits of Scott County represent of seven formations: DeForest, Noah Creek (~Henry Fm. of Illinois), Peoria, Pisgah (~Roxanna Silt of Illinois), Glasford, Wolf Creek, and Alburnett formations as well as unnamed erosion surface sediments. Hudson-age deposits associated with fine-grained alluvial and colluvial sediments include the DeForest Formation which is subdivided into the Camp Creek, Roberts Creek, Gunder and Corrington members. The Noah Creek Formation includes coarse sand and gravel located along the Wapsipinicon River associated with the development of the Iowan Erosion Surface. Unnamed erosion surface sediments consist of reworked till and slopewash deposits formed by peri-glacial activity during the Wisconsin maximum and may be up to 25’ thick. Peoria Formation eolian materials consist of loess and eolian sand of Peoria Formation materials are present throughout the majority of Scott County except on the area south of the Wapsipinicon River mapped as IES materials. Pisgah Formation loess is also present, being thicker near the Mississippi River and thinning to the west. The characteristics of the eolian deposits vary throughout Scott County. The southeast portion of the county adjacent to the Mississippi River is dominated by thick (up to 60’) loess with almost no eolian sand. An adjacent band comprises the center of the county and is dominated by interbedded silt and fine sand. Areas adjacent to Mud Creek are dominated by loess up to 20’ thick. A buried sand sheet is present in the northwest part of the map area and extends into Cedar County. Illinoian-age deposits are limited to Glasford Formation Kellerville till member materials and are only exposed in steeper drainages dominantly in the southern and eastern portions of Scott County. Undifferentiated Pre-Illinoian till is exposed in the map area northwest of Mud Creek in deep drainages; elsewhere it is covered by Wisconsin eolian deposits.
Bedrock exposed at the land surface is restricted to small areas in the eastern, north-central, southern and northwestern portions of the county and all rock outcrops and quarries are located in close proximity to surface topographic lows coincident with the modern drainages of the Mississippi and Wapsipinicon rivers and their tributaries Duck Creek, Walnut Creek, McDonald Creek and Dodges Creek. Throughout the remainder of the county bedrock is covered by moderately thick glacial sediments. Bedrock units consist of Ordovician, Silurian, Devonian and Pennsylvanian formations. The oldest unit at the bedrock surface is the Maquoketa Formation, a thick sequence of shale and dolomite. Silurian strata comprise the largest area of the bedrock surface across the county (Witzke, 1994), and include the combined Hopkinton and Blanding formations (cherty and moderately fossiliferous dolomite), the Scotch Grove Formation (moderately to abundantly fossil-moldic dolomite), and the Gower Formation (laminated to moderately fossilliferous dolomite). Devonian strata include the Wapsipinicon Group (limestone, dolomite and minor shale, partly breciated), the Cedar Valley Group (fossiliferous limestone and dolomite, variably argillaceous), and the Lime Creek Formation (shale and siltstone, abundant conodont fauna). Pennsylvanian System strata of the Raccoon Creek Group (dominated by shale, mudstone and sandstone with subordinate coal and minor limestone) comprises the youngest bedrock map unit in the county (Pope and Anderson, 2009; Witzke et al., 2010).
References Anderson, W.I., and Garvin, P.L. (eds), 1984: The Cedar Valley Formation (Devonian), Black Hawk and Buchanan counties:
Carbonate Facies and Mineralization, area. Geological Society.of Iowa, Guidebook 42, 47 p. Anderson, R.R., and Bunker, B.J. (eds), 1998: Fossil shells, glacial swells, piggy smells, and drainage wells: the geology of the
Mason City, Iowa, area. Geological Society.of Iowa, Guidebook 65, 71 p. Belanski, C.H., 1927: The Shellrock Stage of the Devonian. American Midland Naturalist, v. 10, p. 316-370. Bettis, E.A., III, 1989, Late Quaternary history of the Iowa River Valley in the Coralville Lake area in Plocher, O.W., Geologic
Reconnaissance of the Coralville Lake area: Geological Society of Iowa Guidebook 51, p. 93-100. Boellstorff, J., 1978a, North American Pleistocene Stages reconsidered in light of probable Pliocene-Pleistocene continental
glaciation: Science, v. 202 p. 305-307. Boellstorff, J., 1978b, Chronology of some late Cenozoic deposits from the central United States and the ice ages: Transactions
of the Nebraska Academy of Science, v. 6, p. 35-49. Day, J., Luczaj, J., and Anderson, R. (eds), 2006: New perspectives and advances in the understanding of lower and middle
Paleozoic epeiric carbonate depositional systems of the Iowa and Illinois basins, In Guidebook for the 36th Annual Field Conference of the Great Lakes Section, Society for Sedimentary Geology (SEPM) and the 67th Annual Tri-State Field Conference, September 29 – October 1, 2006, 167 p.
Esling, S.P., 1984, Quaternary stratigraphy of the lower Iowa and Cedar River valleys, southeast Iowa: University of Iowa, Iowa City, unpublished Ph.D Dissertation, 451p.
Groves, J.R., Walters, J.C., and Day, J. (eds), 2008: Carbonate platform facies and faunas of the Middle and Upper Devonian Cedar Valley Group and Lime Creek Formation, northern Iowa. IGS Guidebook 28, 96 p.
Hallberg, G.R., 1980, Pleistocene stratigraphy in east-central Iowa: Iowa Geological Survey Technical Information Series 10, 168p.
Hallberg, G.R., 1986, Pre-Wisconsin glacial stratigraphy of the central plains region in Iowa, Nebraska, Kansas, and Missouri: in Richmond, G.M. and Fullerton, D.S., eds., Quaternary Glaciations in the United States of America, Report of the International Correlation Programme-Project 24: in Sibrava, V., Bowen, D.Q., and Richmond, G.M., (eds.), Quaternary Science Reviews, Quaternary Glaciations in the Northern Hemisphere, v. 5, p. 11-15.
Hallberg, G.R., Lineback, J.A., Mickelson, D.M., Knox, J.C., Goebel, J.E., Hobbs, H.C., Whitfield, J.W., Ward, R.A., Boellstorf, J.D., and Swinehart, J.B., 1991, Quaternary geologic map of the Des Moines 4° x 6° quadrangle, United States. U.S. Geological Survey, Miscellaneous Investigations Series, Map I-1420, 1:100,000 scale map sheet.
Hershey, H. G., 1969, Geologic map of Iowa, Iowa Geological Survey, scale 1:500,000 (out of print). Koch, D.L., 1970: Stratigraphy of the Upper Devonian Shell Rock Formation of north-central Iowa. IGS Report of Investigations
10, the state of Iowa, 123 p. Leverett, F. 1898. The weathered zone (Yarmouth) between the Illinoian and Kansan Till, Journal of Geology v. 6: 238-243. Leverett, F. 1899. The Illinois glacial lobe: U.S. Geological Survey Monograph, 38, 817p. Lineback, J.A., 1980, The Glasford Formation of western Illinois: Iowa Geological Survey Technical Information Series, no. 11,
181-184. Norton, W. H., 1899, Geology of Scott County: Iowa Geological Survey, Vol. 9, pp. 389-519. Prior, J.C., 1976, Landforms of Iowa: Iowa City, University of Iowa Press, 154 p. Prior, J.C. and Kohrt, C.J., 2006, The Landform Regions of Iowa, Iowa Geological Survey, digital map, available on IDNR GIS
Library-ftp://ftp.igsb.uiowa.edu/gis_library/ia_state/geologic/landform/landform_regions.zip; ttp://www.igsb.uiowa.edu/nrgislibx/
Pope, J.P. and Anderson, R. A., 2009, Revision of stratigraphic nomenclature and reclassification of the Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian stages in Iowa, Geological Society of America Abstracts with Programs, v. 41, No. 2, p. 33.Prior, J.C. and Korht, C.J., 2006, The Landform Regions of Iowa, Iowa Geological Survey, digital map, available on IDNR GIS Library- ftp://ftp.igsb.uiowa.edu/gis_library/ia_state/geologic/landform/landform_regions.zip; http://www.igsb.uiowa.edu/nrgislibx/
Quade, D.J., Bettis, E.A. III, and Giglierano, J.D., 2004, Surficial geologic materials of the McCausland Quadrangle, Iowa Geological Survey Open File Map 04-5, 1:24,000 scale map sheet.
Quade, D.J., Tassier-Surine, S.A., McKay, R.M., Giglierano, J.D., and Bettis, E.A., III, 2005, Surficial geologic materials of the Eldridge 7.5'' Quadrangle, Scott County, Iowa, Iowa Geological Survey Open File Map 05-5, 1:24,000 scale map sheet.
Quade, D.J., Tassier-Surine, S.A., McKay, R.M., Giglierano, J.D. and Bettis, E.A., III, 2008, Surficial Geology of Cedar County, Iowa Final Phase: Surficial Geologic Map of Cedar County, Iowa, Iowa Geological and Water Survey Open File Map 08-8, 1:100,000 scale map sheet.
Ruhe, R.V., 1969, Quaternary Landscapes in Iowa: Ames, Iowa State University Press, 255p. Tassier-Surine, S.A., Quade, D.J., Liu, P., Giglierano, J.D., and Bettis, E.A., III, 2005, Surficial geologic materials of the Dixon
7.5'' Quadrangle, Scott County, Iowa, Iowa Geological Survey Open File Map 05-4, 1:24,000 scale map sheet. Tassier-Surine, S., Quade, Deborah, Bettis, E.A., III, McKay, R., Liu, H. and Giglierano, J., 2009a, Surficial Geology of the
Davenport West 7.5’ Quadrangle, Scott County, Iowa, Iowa Geological and Water Survey Open File Map 09-6, 1:24,000 scale map sheet.
Tassier-Surine, S., Quade, Deborah, Bettis, E.A., III, McKay, R., Liu, H. and Giglierano, J., 2009b, Surficial Geology of the Davenport East 7.5’ Quadrangle, Scott County, Iowa, Iowa Geological and Water Survey Open File Map 09-7, 1:24,000 scale map sheet.
Walters, J.C., 1996, General and Environmental Geology of the Cedar Falls/Waterloo Area, The Iowan Surface, in General and Environmental Geology of Cedar Falls/Waterloo and Surrounding Area, Northeast Iowa: Iowa Geological Survey Guidebook Series No. 22, p. 7-9.
Wickham, J.T., 1979, Pre-Illinoian till stratigraphy in the Quincy, Illinois area; in the 43rd annual Tri-State Geological Field Conference, Ilinois State Geological Survey Guidebook 14.
Willman, H.B. and Frye, J.C., 1970, Pleistocene stratigraphy of Illinois: Illinois State Geological Survey Bulletin, 94, 204p.
Witzke, B.J., Anderson, R.R. and Pope, J.P., 2010, Bedrock Geologic Map of Iowa, scale: 1:500,000, Iowa Geological and Water Survey, Open File Digital Map OFM-10-1.
Witzke, B. J., 1994, Silurian Stratigraphy in the Quad Cities Area, Iowa-Illinois, in Paleozoic Stratigraphy of the Quad-Cities Region East-Central Iowa, Northwestern Illinois, Geological Society of Iowa Guidebook 59, p. 3-15.
Witzke, B.J. and Bunker, B.J., 1984: Devonian stratigraphy of north-central Iowa. IGS Open File Report 84-2, p. 107-149. Witzke, B.J., Bunker, B.J., and Rogers, F.S., 1988: Eifelian through lower Frasnian stratigraphy and deposition in the Iowa area,
central midcontinent, U.S.A. in McMillan, N.J., Embry, A.F, and Glass, D.J. (eds.): Devonian of the World, Canadian Soc. Of Petroleum Geologists, Memoir 14, vol. I, p. 221-250.
LEGEND
CENOZOIC
QUATERNARY SYSTEM
HUDSON EPISODE Qal - Al luvium (DeForest Formation-Undifferent iat ed) Variabl e t hi ckness of l ess t han 1 to 5 m (3-16 ft) of very dark gra y to brown, noncal careous to cal careous, strati fi ed silt y c lay loam, cl ay loa m, loam to sandy loam al luvium and colluvium in stream va lleys, on hill slopes a nd in closed depressions. Ma y overli e Glasford or Pre-Ill inoian forma tion glac ial til l, Peori a Forma tion loess or eoli an sa nd, or Noah Creek Forma tion 2 sand and gravel. Assoc iate d with l ow-reli ef modern fl oodplain, c losed depressions, modern dra ina gewa ys or toeslope posit ions on the l andscape. Sea sonal high water ta bl e and pote ntia l for frequent flooding. Qall t - Wapsipinicon and Mississippi Rive r Vall ey – Low Ter race (DeForest Format ion-C amp C ree k Mbr. a nd Robert s Creek Mbr. ). Variabl e t hi ckness of l ess than 1 to 5 m (3 -16 ft ) of very da rk gray to brown, noncalca re ous, strati fi ed silt y clay loam, loa m, or clay loam, associa ted with t he modern channel bel t of the Wapsipinic on River valle y. Overli es Noah Creek Formation 2. Occupies lowest posi ti on on the fl oodplain ie. modern channel be lts. Sea sona l high water table a nd frequent flooding potent ial . Qali -ht - Wapsipinicon and Missi ssippi River Val ley – Intermediate-High Terrace (DeForest Format ion-Gunder Mbr. ). Va ri abl e thickness of less than 1 t o 5 m (3-16 ft ) of very dark gra y to brown, noncal careous, sil ty clay loam to loa m a lluvium or colluvium. Overli es Noah Creek Formation 2 a long the Wapsipinic on R iver or the He nry Formation along the Missi ssippi River. Occupies t errace and val ley margin positi on 1 t o 2 m (3-7 ft) above the mode rn fl oodplain. Seasonal high wate r t abl e and low to moderate fl ooding potenti al. Qali -htb - Missi ssippi Rive r Vall ey – Intermediate-High Terr ace (DeForest Formation-Gunder Mbr.). Variable t hi ckness of l ess t han 1 to 5 m (3-16 ft) of very dark gray to brown, noncal careous, silt y clay loa m to loa m alluvium or c olluvium. Overl ies Devonian C edar Vall ey Group limestone a long the Mississippi River near B uffalo. Occupies terra ce and vall ey margin posi tion 1 to 2 m (3 -7 ft) above the modern fl oodplain. Seasonal high water t abl e and low to moderat e fl ooding potenti al. Qaf - Al luvial fan (Corrington Mbr.) Vari abl e thickness of 2 t o 5 m (7-16 ft ) of dark brown to yellowish brown, nonc alcreous, sil t l oam to l oam with interbedded le nses of fine sand and si lts. A pebble lag i s c ommonly found a t or near the fan surface. Overl ies thi ck sand a nd gravel of t he Noah Creek Formation 2 (along the Wapsipinic on River) or Henry Formation (along the Mississippi River). Steep angled fans occur at the ba se of low order drainages and col luvial slopes along the northern margin of t he Mississippi R iver Vall ey.
HUDSON AND WISCONSIN EPISODE
Qnw2 - Sand and Gravel (Noah Creek Format ion) 2 t o 8 m (7-26 ft ) of yel lowish brown to gra y, poorly t o well sorted, massive to wel l strat ified, coa rse t o fi ne feldspathic qua rt z sand, pebbly sa nd and gravel with few int ervening layers of silt y clay. Along the Wapsipini con River a t hin mant le of loe ss, re worked loess, or fi ne-grained alluvium may be prese nt. This unit includes sil ty col luvial deposit s derived from the adjacent ma p uni ts. In pl aces t hi s unit is ma ntl ed with 1 to 3 m (3 -10 ft ) of fine t o medium, well sorted medium to fine sand derived from wind re working of t he all uvium. This unit enc ompasses deposits t hat accumulat ed in low-reli ef stream val leys during the Wisconsin a nd Hudson epi sodes. Seasonal high water ta ble .
WISCONSIN EPISODE
Qe - Sand Dunes and Sand She ets (Peori a Formation-sand faci es) Generally l ess t han 3 m (10 ft) of yel lowish brown, massive, ca lcareous l oamy sand to fine sand. It may overl ie yel lowish-brown coa rse-grained sa nd and grave l (Noah C re ek Fm. 2) or l oa my Iowa n Erosion Surface materi als. Usually restricte d to a narrow belt south of the Wa psipinicon River Va lley. Qnw - Sand and Gravel (Noah Cree k Formation) Generally 8 m t o 38 m (26 to 125 ft) of yellowish brown to gray, poorly t o well sorted, massive to well stratifie d, c oarse to fine feldspathic quart z sand, pebbly sand and gravel with few intervening la yers of si lty cl ay. This unit i s shown only in cross sec tion. It is burie d by younger Hudson-a ge al luvial de posit s associat ed with t he Wa psipini con and Mississippi R iver vall eys. This uni t encompa sse s deposit s tha t ac cumulated in ri ver valle ys during the Wisconsin Episode. Qhm - Outwash Sand and Pebbly Sand (Henry Formation, Muscat ine Mbr. ) coa rse to fine sand and pebbly sand mant led with up to 1.5 m (5 ft) of eol ian sand; Kingston T errace complex in the Missi ssippi Valle y. Qhmb - Outwash Sand and Pe bbly Sand Shallow to Bedrock (Henry Formation, Musca tine Mbr. ) c oarse to fine sand and pe bbly sand mantl ed with up to 1. 5 m (5 ft) of eoli an sa nd; Kingston Terrac e complex in t he Mississippi Val ley. Overl ies Si luria n Gower Format ion fossil iferous dolomit es of the Anamosa and LeClaire Members from the northern part of t he quad to north of B ett endorf. From Bet tendorf area south, the deposi t i s benched on Middle Devonia n Wapsipinicon Group dolomi te a nd l imestone a nd or Lower Pennsylva nia n Ra ccoon C reek Group shale, mudstone or sandstone. Qhs - Outwash Sand and Pebbly Sand (Henry Formation, Sabula Mbr.) coarse to fi ne sa nd and pe bbly sand ma ntl ed with up to 5 m (16 ft) of eolia n sand; Sa vanna Terrace complex in t he Missi ssippi Va lley. Qhsb - Outwash Sand and Pebbly Sand Shallow to Bedroc k (Henry Forma tion, Sa bula Mbr.) coarse t o fi ne sa nd and pebbly sand ma ntl ed wi th up to 5 m (16 ft) of eol ian sand; Savanna Ter rac e complex in t he Mississippi Va lle y. Overl ies Silurian Gower Format ion fossi liferous dolomit es of the Anamosa and LeC laire Members from the northern part of the quad to north of B ette ndorf. From Bet tendorf area south, the deposi t i s benched on Middle Devonia n Wapsipinicon Group dolomi te a nd l imestone a nd or Lower Pennsylva nia n Ra ccoon C reek Group shale, mudstone or sandstone. Qpt - Loess Mantl ed Ter race (Peoria Forma tion –silt and/or sand facies) 2 to 7 m (7-23 ft ) of yellowish brown to gray, massive, j ointed, ca lcareous or non calca reous, si lt loa m and intercal ated fine to medium, well sorte d, sa nd. May gra de downward to poorly t o moderately wel l sort ed, moderat ely to well strati fi ed, coarse t o fi ne feldspathi c quartz sand, l oam, or silt loam al luvium (Late Pha se High Terrac e) or may overlie a Farmdale Geosol developed in Pisgah Silt which in turn overli es a wel l-expressed Sangamon Geosol developed in poorly to moderate ly well sort ed, modera tely to well strati fi ed, coarse t o fine sand, loam, or si lt loam al luvium (Ea rly Phase Hig h Terrace). The Pisgah Formation is in t he same st rat igraphic posi ti on a s the Roxanna Sil t whic h i s ma ppe d in Illi nois. Qptlp - Late Phase High Terr ace (LPHT ) (Peoria Formation-sil t and/or sand faci es) 2 to 7 m (7 -23 ft) of yel lowish brown to gray, massive, joint ed, ca lcareous or nonca lcareous, si lt l oam and intercala ted fi ne t o medium, wel l sort ed, sand. Grade s downward to poorly to moderat ely wel l sort ed, moderat ely to wel l strati fi ed, coarse t o fine feldspathic quartz sand, loam, or sil t l oam al luviu m. Qptep - Early Phase High Te rrac e (EPHT) (Peori a Formation-sil t and/or sand facie s) 2 t o 7 m (7-23 ft) of yel lowish brown to gray, massive, j ointed, calca reous or noncalcareous, silt l oam a nd intercala ted fi ne t o me dium, we ll sort ed, sand. The Peoria deposit s overl ie a Farmda le Geosol deve loped in the Pisgah Forma tion which in turn ove rl ies a wel l-expressed Sangamon Geosol developed in poorly to modera tely well sorted, moderately t o wel l st rat ifi ed, coarse to fi ne sa nd, l oam, or silt loam al luvium. The Pisga h Formation is in the same st rat igraphic positi on as t he R oxanna Silt which i s mapped in Ill inois. Qps - Loess (Peoria Format ion—silt fa cies) Genera lly 2 to 8 m ( 7 -26 ft) of yel lowish to grayish brown, ma ssive, joint ed calcareous or noncal careous silt loam to si lty cla y loam. Overlie s a gra yish brown to ol ive gra y si lty cl ay loam to si lty cl ay (Pi sgah Format ion—eroded Farmdale Geosol) whic h is l ess than 1.5 m (5 ft) t hi ck. T he Pi sgah Format ion is i n the same st rat igraphic posit ion as the Roxanna Si lt which i s mapped in Illi nois. The Farmdale Geosol appears to be di sturbed by periglaci al acti on and is welded to an older Sa nga mon Geosol de velope d in loa my glaci al til l of t he Wolf Creek or Alburnett formations. Thi s mapping unit encompasses upland divide s, ri dgetops and convex sideslope s. Well to somewhat poorly drained landscape. Qps1 - Loess and Interc alated E ol ian Sand (Pe oria Formation-sil t faci es) 2 to 10 m (7-33 ft ) of yel lowish brown to gray, massive , fra ctured, nonca lcareous grading d ownwa rd to cal careous silt loam and inte rcal ate d fine t o me dium, well sorted, sa nd. Sand i s most abundant in l ower part of t he eol ian pa ckage- eol ian dunes 0. 5 t o 2.5 m (2-8 ft) t hick may be present at the ba se of thi s unit . Overli es massive , fractured, loa my glacia l ti ll of the Wol f C reek or Alburnett format ions with or without interve ning c laye y Farmdale /Sangamon Geosol. Qps-gla - Loess (Peoria Formation—sil t fa cies) Ge nerally 2 to 8 m (7-26 ft ) of yellowish to gra yi sh brown, massive, jointed cal careous or nonca lcareous sil t loam to si lt y clay loam. Overli es a grayi sh brown to olive gra y sil ty cla y loam to si lty cla y (Pisga h Formation - eroded Fa rmda le Geosol) which i s less t han 1. 5 m (5 ft ) thick. The Pisga h Formation is i n the same strati graphic po si tion a s the R oxanna Sil t which i s mapped in Ill inois. The Fa rmda le Ge osol appea rs to be disturbed by perigl acia l a cti on and is welded to a n older Sangamon Geosol developed in loa my glaci al ti ll of the Glasford Forma tion. Thi s ma pping unit e ncompasses upland divides, ri dgetops and convex sideslopes. Wel l t o some wha t poorly drained landscape. Qpsb-gla - Thick Loe ss (Peoria Formation- sil t fac ies) Generally 5 to 15 m (16-49 ft) of yel lowish to grayi sh brown, massive, joint ed calc are ous or noncal careou s sil t loam to silt y cla y loam. Overlie s ma ssive, frac tured, cla y loa m gla cial ti ll of t he Gla sford Forma tion with or without i nte rvening cla yey Farmda le Geo sol and Pisga h Formation materia ls. T he Pi sgah Format ion i s in t he sa me strati gra phic posit ion as t he R oxa nna Silt which is mapped in Il linoi s. Thi s ma pping unit encompasses upland divide s, ri dgetops and convex sideslope s. Well t o somewhat poorly drained landscape. Qps1b-gla -T hic k Loess and I ntercalated E olian Sand (Peoria Formation-sil t faci es) 5 to 15 m (16-49 ft) of yellowish brown to gray, massive, noncal careous grading downward to cal care ous silt loam and int ercalat ed fi ne to medium, wel l sort ed, sand. Minimum thickness of 5 m (16 ft) on uplands. Maximum thickne ss of 2 -7 m (7-23 ft ) of l oess occurs on adj acent slopes. Overlie s massive, fractured, loamy glacia l ti ll of the Illi noian Gla sford Format ion with or without i ntervening clayey Farmdale /Sangamon Geosol . Qps2_gla - Eolian Sand and Inte rcalated Si lt (Peoria Formation—sa nd fa cies) General ly fi ve t o fi ft een meters (16 to 49 feet) of yellowish brown to gra y, moderat ely to wel l st rat ified noncal careous or calca reous, fine t o medium, wel l sorted, eol ian sand. Ma y contain int erbeds of yellowi sh brown to gra y, massive, si lt loam loe ss. Overlie s massive, fractured, l oamy glacia l til l of the Ill inoian Glasford Forma tion with or without i nt ervening clayey Farmdale /Sangamon Ge osol . Qgla2 - Loamy and Sandy Sediment Shallow to Glacial T ill (Unnamed erosion surfac e sediment ) 1 t o 3 m (3 -10 ft) of ye llowish brown to gray, massive t o weakly strati fi ed, wel l to poorly sorted loamy, sandy and si lt y erosion surfac e sediment . Map unit includes some a reas mant led with less tha n 2 m (7 ft) of Peoria sil t or sand. Overli es massive, fractured, firm glaci al ti ll of the Ill inoian Glasford Forma tion. Sea sonal ly high water tabl e may occur in thi s ma p uni t.
ILLINOIS EPISODE Qgla - T ill (Glasford Format ion) Ge nerally 3 t o 10 m (10-33 ft) of very dense, massive, fractured, loa my glaci al til l of the Ill inoian Glasford Forma tion with or without a thin loess mant le (Peori a Format ion—less than 2 m) and intervening cl ayey Farmdale/Sangamon Ge osol . Uppermost t ill may be reworke d (associ ated with the Iowan Su rface). Drainage is variable from well drained to poorly drained.
PRE-ILL INOIS EPISODE Qwa3 - T ill (Wolf C reek or Alburnett format ions) General ly 10 to 35 m (33-115 ft) of ve ry de nse, ma ssive, fractured, loamy glaci al til l of the Wol f Creek or Alburne tt formations with or without a thin loess mantl e (Peoria Format ion—less t han 2 m) a nd int ervening cl ayey Farmdale/Sa nga mon Geosol. Thi s ma pping unit enc ompasses narrowly dissecte d int erfluves a nd side slopes, a nd side val ley slopes. Drainage is va ria bl e from well drained to poorly dra ine d.
PA LEOZOIC
PALEOZOIC ERATHEM
PENNSYLVANIAN SYSTEM Prc - RACCOON CREEK GROUP (primarily Morrowan; locally i ncludes Atokan-lower Desmoinesian Tra dewater Formation in upper pa rt ). Recognized only in eastern Iowa in Scot t and Muscat ine count ies; includes i n a scending order the “ Caseyvill e” and Tradewater formations. Rest s unconformably on older ma p uni ts i n t he county and fi ll s pal eova ll eys a nd pal eokarst develope d in underlying Siluri an and Devonia n carbonate rocks. Prima ry li thologie s are: shale /mudstone, l ight to da rk g ray, partly sil ty t o sandy; sa ndstone , very fine t o me dium grained; si ltstone, gray. Secondary l ithologies are: ca rbona ceous sha le/mudstone, gray to black; phospha tic bla ck shale; limestone, dense, partl y fossil iferous, partl y sandy ; coal (beds l ocal ly > 2 ft). Minor lit hologies a re: sandstone, coarse grained to granular, partly conglomerati c; mudstone, red to pink; l imestone concret ions (may be septarian); cone-in-cone l imestone; sideri te/ ironstone concretions and pel let s; pyri tic . Ma ximum thi cknesses: 195 ft (59 m).
D EV ONIAN SYSTEM Dl - LIME CREEK FORMATION (Upper Devonian, upper Frasni an). The format ion i s comprise d entirely of t he Sweetl and Creek Shale i n the southwest portion o f the county. Primary li thologies are li ght green to brown shale, and green silt stone c ontaining an abunda nt and diverse fossil conodont fauna . Ma ximum thi ckness to 12 ft (4 m). Dc – CEDAR VAL LEY GROUP (Middle-Upper Devonian, middle Giveti an-lower Frasni an). The group includes in ascending order the Li ttl e Cedar, Cora lvi lle, a nd Lithograph C ity formations. Primary lit hologies a re: fossili ferous lime stone, with an abundant and diverse inverte bra te fauna, variably argill aceous, par tly biostromal ; and dolomit e, pa rt ly fossi l-moldic t o vuggy, variably argil lac eous. Maximum thickness of 85-90 ft (26-27 m) occurs in the southwest porti on of the county near Buffalo. Dw - WAPSIPINICON GROUP (Middle Devonian, upper Eifel ian-middle Givet ian). The group include s in ascending order t he B ert ra m, Otis, and Pini con Ridge forma tions. Primary lit hologies a re: dolomi te, part ly laminated, variably argill aceous, pa rt fet id; and limestone, dense, “sublit hogra phic”, partly lamina ted to i ntracl astic; dolomi te, fossil -moldi c to vuggy (lower Otis fm). Seconda ry li thologie s are: l imestone/dolomit e brecc ia (evapori te coll apse, upper Pinicon R idge Fm); dolomiti c sha le and shaly dolomit e, gra y to green-gray, part ly silt y-sandy; limestone , part ly pe loidal -ooli tic to fossili ferous (Ot is Fm). Minor l ithologies are: chert a nd chal cedony nodules (Pinicon Ridge Fm); and sandstone, fi ne to medium wi th larger dolomite cla st s (B ertra m Fm). Ma ximum thi cknesses of 112 ft (34 m).
SILURIAN S YSTEM Sg - GOWER FORMAT ION (Lower-?Uppe r Si lurian, Wenloc k-?Ludlow). The format ion includes Anamosa and LeClaire members; LeClaire Member ca n be a fossili ferous carbona te mound faci es or a hori zontally stra tified fossil -moldi c facie s. Erosional ly beveled and t runca ted be neath Dw. Primary li thologie s are: l amina ted to stromatoli tic dolomit e (Anamosa Mbr), pa rt feti d/organic; dolomit e mudstone, dense, featureless. Se condary lit hologies a re: dolomite, fossil iferous to vuggy, moldic,; dolomi te, pa rt ly coa rsely crystall ine, vuggy, fossil iferous to sparsely fossil iferous, part crinoidal and coral line (LeClai re Mbr). Minor l ithologies are: chert; intra clasti c dolomi te. Maximum thickness occurs at LeCla ire, 150 ft (46 m); t hins to the southwest to 70 ft (21 m) at Blue Grass. Ss - SCOTCH GROVE FORMATION (Lower Silurian, upper Lla ndovery-lower Wenlock). The formation includes the Johns Creek Quarry, Welton, B uck Creek Quarry, Waubeek, and Pali sa des-Ke pler members. The bulk of t he format ion i s comprised of the finely fossil -moldi c Welton Me mber. Ca rbona te mound fa cies of t he Palisa des-Kepler Member are repla ced lat era lly by inter-mound strata of the Waubeek Member. Everywhere overl ain by Sg. Primarily lit hologies are: dolomi te, porous, fossil -moldi c t o vuggy, part very crinoidal (includes Wel ton Mbr); dolomit e, cherty t o very che rty, dense (B uck C re ek Quarry Mbr). Seconda ry lit hologies are: dolomi te, spa rsely fossil-moldic, dense, part vuggy (include s Waubeek Mbr); dolomit e, coarsely crystall ine, part very crinoidal (within Johns Creek Quarry and Pa lisades-Kepler mbrs); dolomite mudstone , de nse. Minor l it hologies are: dolomite, slight ly a rgill aceous; quartz druse, c halc edony, sili cified fossils. Maximum thicknesses of 150 ft (46 m). Sh – HOPKINTON AND BL ANDING formations (Lower Siluri an, ?Rhuddanian, Aeronian-upper Llandovery. The Blanding Forma tion marks t he base of the Siluri an in t he county and i s overl ain by the substantial ly thicker Hopkinton Formation. The map uni t i s at the bedrock surface only wi thin t he deeply buri ed bedrock va lle y (Cle ona Cha nnel) in the northern and we st ern part of c ounty. Primary li thologie s are: dolomi te, fossil -moldi c t o vuggy, fine t o coarse crystal line; dolomi te, dense to porous, c herty t o very cherty, nodular to be dded che rt (espec iall y Bla nding Fm). Maximum map-unit thicknesses of 110 ft (35 m); Hopkinton 95 ft (30 m); B landing 15 ft (5 m). This uni t i s shown only in t he cross se ction.
OR DOVICIAN SYSTEM Om - MAQUOKET A FORMATION (Upper Ordovicia n; Ric hmondian [upper Kat ian]). T he formation includes in asce nding order the Elgin, Clermont , Fort Atkinson, and Brainard me mbers. The map unit is at the be drock surfa ce only within the de eply buried bedrock vall ey (C leona C hannel ) in the northern part of county. Primary li thologies are: shale , gre en-gray, varia bly dolomiti c, mostly unfossi li ferous; dolomite , argi lla ceous, part ly shaly, variably fossili ferous; dolomit e, part ly argil lace ous, partl y c herty. Seconda ry li thologie s are: shale, brown to brown-gray, organic, pa rtl y graptoli tic, partl y fi nely la minat ed (lower st rat a); interbedded dolomi te a nd shal e, part ly fossili ferous. Minor lit hologies are: dolomi te, phospha tic, argil lac eous (Elgin Mbr.). Maximum thicknesses of 210 ft (64 m). Thi s unit i s shown only in the cross section. Qf – Fil l Areas of major land fil ling. Fi ll associa ted wi th rai lroad grade s, higway gra des, a nd land l evel ing. Variabl e t exture. Dr ill Holes to Bedroc k Water Wel l Recor ds
Qf
