BEDROCK GEOLOGY OF THE DAVENPORT EAST 7.5’ QUADRANGLE, Bedrock Geology of the Davenport East (Iowa) SCOTT COUNTY, IOWA

Iowa Geological Survey 7.5' Quadrangle Open File Map OFM-09-04 June 2009

prepared by

90°37'30"W 90°35'0"W 90°32'30"W 90°30'0"W Huaibao Liu, Robert McKay, Stephanie Tassier-Surine, James Giglierano, and Robert Rowden

Iowa Geological Survey, Iowa City, Iowa

41°37'30"N 41°37'30"N

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Iowa Department of Natural Resources, Richard A. Leopold, Director Iowa Geological Survey, Robert D. Libra, State Geologist Sg

Supported in part by the U.S. Geological Survey Cooperative Agreement Number 08HQAG0082 National Cooperative Geologic Mapping Program (STATEMAP)

Pcc ACKNOWLEDGMENTS

New subsurface geologic data was generated by the University of Iowa students Sarah Byram and Kyle Bracken who produced descriptive logs of water well drill samples. Deborah Quade of Iowa Geological Survey (IGS) lent support with Quaternary field and office expertise; Murray Perdue (IGS) prepared well samples for stratigraphic logging; Ray Anderson (IGS) provided updated bedrock topography data; Brian Witzke (IGS) provided valued information concerning the Silurian and Devonian stratigraphy of the area; and Sg Chris Kahle and Andy Asell (IGS) provided GIS mapping technical help.

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Sg LEGEND Correlation of Map Units

Dw CENOZOIC

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QUATERNARY SYSTEM S E E I T R AGE S MAP E Y 41°35'0"N Qu - Undifferentiated unconsolidated sediment Consists of loamy soils developed in loess and glacial STAGE S 41°35'0"N (Ma) S UNIT Sg Qu till of variable thickness, and alluvial clay, silt, sand and gravel , with a maximum thickness locally exceeding 60 m (200 ft). Unit shown only on cross-section, not on map. QUATERNARY Qu 2.58 Sg PALEOZOIC

N e Dw PENNSYLVANIAN SYSTEM l Desmoinesian A d Pcc I 310 d N i Pcc

A M Atokan B Pcc – Shale, Siltstone and Sandstone (Cherokee Group and Caseyville Formation undifferentiated) Lower V

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Pcc and Middle Pennsylvanian. The thickness of this unit may exceed 30 m (100 ft) in the west central map Y r S

area, but in general is less than 10 m (30 ft). Primary lithology includes gray shale, siltstone, and minor e Pcc N sandstone. Secondary lithologies include black carbonaceous shale and coal; plant fossils, pyrite, and 315 w N o Morrowan L siderite pellets & concretions may be present. E

P Dw DEVONIAN SYSTEM

Sg D Dw - Dolomite, Limestone, Shale, and minor Sandstone (Wapsipinicon Group) Middle Devonian. This D N

map unit includes the Otis and the Pinicon Ridge formations, with a total thickness between 18 and 29 m A Givetian

Dw I e l

390 N

(60-95 ft). The Otis Formation is dominated by lithographic to sublithographic, pelletal limestone, with d d O minor dolomite near its base. The Pinicon Ridge Formation is characterized by laminated or brecciated, i Dw

Pcc V unfossiliferous limestone and dolomite with minor shale. M E

D Dw 395 Eifelian SILURIAN SYSTEM

Sg - Dolomite (Gower Formation) Silurian. Thickness of this formation ranges between 27 and 37 m (90- Sg 120 ft), and the lithology is dominated by porous dolomite, in part laminated and vuggy. Brachiopods and

Sg corals are common in mounded facies. n a i Ludfordian w o

Ss - Dolomite with minor Chert (Scotch Grove Formation) Lower Silurian. The thickness of this interval l d

Ss ranges between 37-45 m (120-150 ft), and is characterized by fossil moldic (especially crinoidal) dolomite. u L Gorstian Vugs and pores are common in most parts, and minor chert may occur in lower part of the formation. Unit 423 shown only on cross-section, not on map. n D a w i

k Homerian Sg Dw D c o l

Drill Holes n e N

W Sheinwoodian A 428 I

D R D D Outcrops D U Ss L I S

n Telychian a i

41°32'30"N 41°32'30"N r e

Dw v Pcc D o D d D D 436 n

D a L

L Aeronian Sg 439 Rhuddanian Dw

Pcc Adjacent 7.5' Quadrangles D Dw Locator Map

LYON OSCEOLA DICKINSON EMMET WINNEBAGO WORTH MITCHELL HOWARD WINNESHIEK ALLAMAKEE

Dw KOSSUTH

MCCAUSLAND SIOUX ELDRIDGE OBRIEN CLAY Dw DONAHUE PALO ALTO HANCOCK CERRO GORDO FLOYD CHICKASAW

FAYETTE CLAYTON

PLYMOUTH HUMBOLDT BREMER CHEROKEE BUENA VISTA POCAHONTAS WRIGHT FRANKLIN BUTLER Sg BLACK HAWK BUCHANAN DELAWARE DUBUQUE WOODBURY WEBSTER P IDA SAC cc CALHOUN HAMILTON HARDIN GRUNDY

JACKSON JONES Sg Sg BENTON LINN MONONA CRAWFORD TAMA CARROLL GREENE BOONE STORY MARSHALL

CLINTON A DAVENPORT_W DAVENPORT_E SILVIS CEDAR HARRISON SHELBY AUDUBON GUTHRIE DALLAS POLK JASPER POWESHIEK IOWA JOHNSON SCOTT

MUSCATINE

POTTAWATTAMIE CASS ADAIR MADISON WARREN MARION MAHASKA KEOKUK WASHINGTON

LOUISA

MILLS MONTGOMERY ADAMS UNION CLARKE LUCAS MONROE WAPELLO JEFFERSON HENRY DES MOINES

FREMONT PAGE TAYLOR RINGGOLD DECATUR WAYNE APPANOOSE DAVIS VAN BUREN ANDALUSIA MILAN LEE

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41°30'0"N 41°30'0"N

90°37'30"W 90°35'0"W 90°32'30"W 90°30'0"W Base map from USGS Davenport East 7.5' Digital Raster Graphic (IGS GIS file DRGB42.TIF) which was scanned from the Davenport East 7.5' Topographic Quadrangle map, published by US Geological Survey in 1991 Topographic contours and land features based on 1986 aerial photography, field checked in 1988 Land elevation contours (10' interval) based on NGVD 1929. 1:24,000 0 0.5 1 2 3 4 Iowa Geological Survey digital cartographic file DavenportEastquad_bedrock09.mxd, version 6/16/09 (ArcGIS 9.2) Miles Map projection and coordinate system based on Universal Transverse Mercator (UTM) Zone 15, datum NAD83.

Kilometers The map and cross section are based on interpretations of the best available information at the time of 0 0.5 1 2 3 4 ± mapping. Map interpretations are not a substitute for detailed site specific studies.

GEOLOGIC CROSS-SECTION A-B

800 A B 800 Duck Creek Black Hawk

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