Surficial Geology of the Stanwood (Iowa) 7.5' Quadrangle
91°15'0"W
91°12'30"W
91°10'0"W
LEGEND
Cenozoic
Quaternary System
91°7'30"W
HUDSON EPISODE
42°0'0"N
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HUDSON and WISCONSIN EPISODE
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Qal2 - Stream Valley Thick Alluvium (DeForest Formation-Undifferentiated) Variable thickness of 2 to 6 meters (6.6 to 20 feet) of very dark gray to
brown, noncalcareous, massive to stratified silty clay loam, loam, sandy loam alluvium and colluvium associated with Pioneer and Walnut Creek stream
valleys. Alluvium overlies an unusually thick, from 6 to 18 m (20 to 60 ft) sequence of medium sand to pebbly sand outwash of the Noah Creek Formation.
Occupies low-relief modern floodplain. Seasonal high water table and potential for frequent flooding.
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Qal - Alluvium (De Forest Formation) One to four meters (3.3 to 13 feet) of massive to weakly stratified, grayish brown to brown loam, silt loam, clay
loam, or loamy sand overlying less than three meters of poorly to moderately well sorted, massive to moderately well stratified, coarse to fine feldspathic
quartz sand, pebbly sand, and gravel and more than three meters of pre-Wisconsin or late Wisconsin Noah Creek Formation sand and gravel. Unit also
includes colluvial deposits derived from adjacent map units. Seasonally high water tables occur in this map unit.
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Qo –Depressions and Fens (DeForest Formation-Woden Mbr.)
Generally 2.5 to 6 meters (8 to 16.5 feet) of black to very dark gray, calcareous, muck, peat and silty clay loam colluvium and organic sediments in drained
and undrained closed and semi-closed depressions. Overlies Noah Creek Fm. sand and gravel in larger stream valleys or may be associated with seeps and
springs along valley walls Usually, associated with stream valley side slopes and areas of exhumed inter-till gravels. Supports wetland vegetation and can be
permanently covered by water. High water table.
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Qe - Sand Dunes and Sand Sheets (Peoria Formation-sand facies) Generally less than 3 meters (10 feet) of yellowish brown, massive, calcareous loamy
sand to fine sand. It may overlie yellowish-brown sand and gravel (Noah Creek Fm.), or reworked unnamed loamy sediments associated with the Iowan
Erosion Surface and/or it may overlie yellowish to grayish brown, often calcareous and fractured clay loam to loam diamicton (Wolf Creek and Alburnett
Formations).
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Qnw2 – Sand and Gravel (Noah Creek Formation) Two to eighteen meters (6.6 to 60 feet) of yellowish brown to gray, poorly to well sorted, massive to
well stratified, coarse to fine feldspathic quartz sand, pebbly sand and gravel with few intervening layers of silty clay. Along Pioneer and Walnut Creek
valleys a thin mantle of loess, reworked loess, fine-grained alluvium (Qal2) may be present. This unit includes silty colluvial deposits derived from the
adjacent map units. In places this unit is mantled with one to three meters of fine to medium, well sorted medium to fine sand derived from wind reworking
of the alluvium. This unit encompasses deposits that accumulated in low-relief stream valleys during the Wisconsin Episode and Hudson Episode. Seasonal
high water table and some potential for flooding.
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WISCONSIN EPISODE
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PRE-ILLINOIS EPISODE
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Qwa2 - Loamy and Sandy Sediment Shallow to Glacial Till (Unnamed erosion surface sediment) One to six meters (3.3 to 20 feet) of yellowish brown to
gray, massive to weakly stratified, well to poorly sorted loamy, sandy and silty erosion surface sediment. Map unit includes some areas mantled with less
than two meters of Peoria Silt (loess). Overlies massive, fractured, firm glacial till of the Wolf Creek and Alburnett formations. Seasonally high water table
may occur in this map unit.
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Qwa1 - Sand and Gravel Shallow to Till (Unnamed erosion surface sediment) One to three meters (3.3 to 10 feet) of yellowish brown to pale brown,
massive to weakly stratified, noncalcareous, medium to coarse, poorly sorted pebbly to cobbly sand with intercalated gravel and loam. Overlies massive,
fractured, firm, loamy glacial till of the Wolf Creek or Alburnett formations. Deposits in this mapping unit are derived primarily from erosion of glacial till in
the adjacent drainage basin. Seasonally high water table may occur in this map unit. Moderate flood potential.
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Qps2 - Eolian Sand and Intercalated Silt (Peoria Formation-sand facies) Five to fifteen meters (16 to 50 feet) of yellowish brown to gray, moderately to
well stratified noncalcareous or calcareous, fine to medium, well sorted, eolian sand. May contain interbeds of yellowish brown to gray, massive, silt loam
loess. Overlies eroded, massive, fractured, loamy glacial till of the Wolf Creek or Alburnett formations or fractured Devonian-age carbonate bedrock.
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Qps1b - Thick Loess and Intercalated Eolian Sand (Peoria Formation-silt facies) Five to fifteen meters (16 to 50 feet) of yellowish brown to gray,
massive, noncalcareous grading downward to calcareous silt loam and intercalated fine to medium, well sorted, sand. Minimum thickness of five meters on
uplands. Maximum thickness of two to seven meters (6.6 to 23 feet) of loess occurs on adjacent slopes. Overlies massive, fractured, loamy glacial till of the
Wolf Creek or Alburnett formations with or without intervening clayey Farmdale/Sangamon Geosol.
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41°57'30"N
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41°57'30"N
Qps1 - Loess and Intercalated Eolian Sand (Peoria Formation-silt facies) Two to ten meters (6.6 to 33 feet) of yellowish brown to gray, massive,
fractured, noncalcareous grading downward to calcareous silt loam and intercalated fine to medium, well sorted, sand. Sand is most abundant in lower part of
the eolian package. Overlies massive, fractured, loamy glacial till of the Wolf Creek or Alburnett formations with or without intervening clayey
Farmdale/Sangamon Geosol.
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Qwa3 –Till (Wolf Creek or Alburnett Formations) Generally 10 to 35 meters (33 to 115 feet) of very dense, massive, fractured, loamy glacial till of the
Wolf Creek or Alburnett Formations with or without a thin loess mantle (Peoria Formation— less than 2 meters or 6.6 feet) or thin loamy sediment mantle
(unamed erosion surface sediment) may overlie intervening clayey Farmdale/Sangamon Geosol. This mapping unit can be buried by unnamed erosion
surface sediments, loess or alluvium and is shown only in the cross-section.
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Paleozoic
Silurian System
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This unit is the primary bedrock aquifer and aggregate resource for Stanwood Quadrangle area. The Gower can range from 0 to 30 meters (0 to 100 feet) in
thickness. It includes laminated unfossilferous and fossilferous mounded facies. Underlying the Gower is the Scotch Grove Formation. The Scotch Grove
includes cherty units, dolostone and mounded facies. The maximum thickness of the Silurian bedrock is approximately 137 meters (450 feet).
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Water Features Rivers, lakes and small ponds formed by blockage of drainage and river channels.
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Qpq - Pits and Quarries Sand and gravel pits and rock quarries. Extent mapped as shown in county soil surveys.
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41°55'0"N
41°55'0"N
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Drill Holes
Drill Holes
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Adjacent 7.5' Quadrangles
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Quadrangle Location
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ANAMOSA
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MORLEY
WYOMING_W
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LYON
OSCEOLA
DICKINSON
EMMET
WINNEBAGO
WORTH
HOWARD
MITCHELL
WINNESHIEK
ALLAMAKEE
FAYETTE
CLAYTON
BUCHANAN
DELAWARE
KOSSUTH
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SIOUX
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OBRIEN
CLAY
PALO ALTO
HANCOCK CERRO GORDO
FLOYD
CHICKASAW
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PLYMOUTH
CHEROKEE
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BUENA VISTA POCAHONTAS
HUMBOLDT
WRIGHT
FRANKLIN
BREMER
BUTLER
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WOODBURY
MECHANICSVILLE
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STANWOOD
IDA
SAC
BLACK HAWK
WEBSTER
CALHOUN
HAMILTON
DUBUQUE
GRUNDY
HARDIN
CLARENCE
JACKSON
JONES
MONONA
CRAWFORD
CARROLL
GREENE
BOONE
STORY
LINN
BENTON
TAMA
MARSHALL
CLINTON
CEDAR
HARRISON
SHELBY
AUDUBON
GUTHRIE
DALLAS
POLK
JASPER
IOWA
POWESHIEK
JOHNSON
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SCOTT
MUSCATINE
POTTAWATTAMIE
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CASS
ADAIR
MADISON
WARREN
MARION
MAHASKA
KEOKUK
WASHINGTON
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LOUISA
CEDAR_BLUFF
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MONTGOMERY
FREMONT
PAGE
TIPTON_W
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MILLS
ADAMS
UNION
CLARKE
LUCAS
MONROE
WAPELLO
JEFFERSON
DAVIS
VAN BUREN
HENRY
DES MOINES
TIPTON_E
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TAYLOR
RINGGOLD
DECATUR
WAYNE
APPANOOSE
LEE
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Base map from USGS Stanwood 7.5' Digital Raster Graphic (IGS GIS file DRGN45C.TIF) which was
scanned from the Stanwood 7.5' Topographic Quadrangle map, published by US Geological Survey in 1965
Topographic contours and land features based on 1963 aerial photography, field checked in 1965
Land elevation contours (10' interval) based on NGVD 1929.
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Iowa Geological Survey digital cartographic file StanwoodQuad07.mxd, version 7/30/07 (ArcGIS 9.1)
Map projection and coordinate system based on Universal Transverse Mercator (UTM) Zone 15, datum NAD83.
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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.
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41°52'30"N
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COOPERATIVE MAPPING WITH THE
NATURAL RESOURCES CONSERVATION SERVICE (NRCS)
SURFICIAL GEOLOGIC MAPS OF THE STANWOOD
AND CEDAR BLUFF 1:24,000 QUADRANGLES
Phase 2
41°52'30"N
91°15'0"W
91°12'30"W
91°10'0"W
91°7'30"W
±
1:24,000
0
0.5
1
0
2
0.5
1
3
2
4
Miles
3
4
Kilometers
Iowa Geological Survey
Open File Map 2007-3
July 2007
Prepared by
Deborah J. Quade, 1 Stephanie Tassier-Surine1, James D. Giglierano1
and E. Arthur Bettis III 2
1
Iowa Geological Survey, Iowa City, Iowa
2University of Iowa, Department of Geoscience
Geologic Cross Section A-B
A
B
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Walnut Creek
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Iowa Department of Natural Resources, Richard A. Leopold, Director
Iowa Geological Survey, Robert D. Libra, State Geologist
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Supported by the U.S. Geological Survey
Cooperative Agreement Number 06HQAG0031
National Cooperative Geologic Mapping Program (STATEMAP)
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Plum River
Fault Zone
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D U
Vertical Exaggeration=20x
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ACKNOWLEDGEMENTS
Elevation (feet above sea level)
Elevation (feet above sea level)
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Recognized for contributions to map’s production: Bob McKay, Brian Witzke, Ray Anderson, Andrew Asell, Pete Kollasch, Katie Foreman, Mary Pat Heitman, and
Lois Bair. Drilling was provided under a contract with Aquadrill of Iowa City, Iowa; a special thanks to Jay Joslyn and drilling crew members who worked at times in
challenging drilling conditions. Especially, thanks to the following individuals who graciously allowed access to their land for drilling: Elsie Becker, Dennis and Linda
Coppess, Ed Fisher, Gary Jackson, Cary Lieser, Duane Litscher, Mike Moes, Brent Montz, Warren Nybergall, Olin Community Schools, Steve Robinson, Victor
Thomsen, and Richard Zenishek. And, thank you to NRCS for contributions of drilling and staff time to complete investigations at three of the drilling sites: Ryan
Dermondy, Jason Steele, Mark Lavan, and Kathy Woida assisted in describing these cores as part of the mapping update for the Iowa Cooperative Soil Survey Update
for Cedar County.