B08_Solicitation_-_Attachment_9_-_Geomorphological_Investigation_Report.pdf

GEOMORPHOLOGICAL INVESTIGATION AT

THE EFFIGY MOUNDS NATIONAL MONUMENT

VISITOR CENTER AND MAINTENANCE/OFFICE AREA

HARPERS FERRY, IOWA

Contract Number 140P6018-D-0001, Task Order 140P6020F0029

HDR Agreement Number 1000100053611

BCA 2780

THIS VOLUME MAY CONTAIN SITE LOCATION INFORMATION

NOT FOR PUBLIC DISTRIBUTION

Prepared for HDR Engineering, Inc.

703 Main Street, Suite 200 Rapid City, South Dakota 57701

Prepared by Jeffrey Anderson

Anderson Geological Services 9769 Edge O’Woods Drive

Cedarburg, Wisconsin 53012

Bear Creek Archeology, Inc.

P.O. Box 347

Cresco, Iowa 52136 Derek V. Lee, Director

January 2021 i

MANAGEMENT SUMMARY

Geomorphological field investigations were conducted for HDR, Sioux Falls, South Dakota, on behalf of the National Park Service for the Effigy Mounds National Monument on September 14 and 15, 2020. The investigation was conducted in the Yellow River Valley a short distance from the Mississippi River near Marquette, Iowa. The project area lies on a complex set of landform sediment assemblages including Holocene alluvial fans, and colluvial slopes.

Most of the project area contained variable amount of fill material at the surface with few areas remaining undisturbed. The most significant disturbance has occurred along the eastern end of the project area near the visitor center. Some locations contain historical sediment deposits below the fill material, while other locations had historical deposits imbedded in the fill material.

The geomorphological work was to determine what landforms lie below the disturbed surface material and determine if cultural potential exists below the fill and into native soils. Giddings probe cores were advanced along two east-west transects in order to examine the soils. The first southern transect included Giddings probes 1–7, and the second northern transect included Giddings probes 8–15. The first southern transect lies on an alluvial fan/terrace complex, while the second northern transect lies along a colluvial slope. In addition, two sampling tube cores were advanced along the western portion of the project area.

The depth of the surface fill is variable across the project area and the contact with the underlying soil is usually disturbed. A mid to late Holocene soil is commonly present underneath the fill and an early to mid Holocene soil also occurs at many of the cored locations. The one definite artifact recovered is a piece of flaking debris recovered from the lower portion of the fill. There is also the potential that in one location a mound remnant is present buried beneath the fill.

Based on the geomorphological investigations buried pre-contact cultural potential exists below the surface disturbance in the buried native surface soil and lower paleosols.

However, in nearly all cases, the surface of the uppermost buried native soil has been disturbed. Generally, the further west along the two transects, the less disturbance occurred in the native soil. Much of the project area is interpreted to have high potential for pre-contact cultural deposits.

INTRODUCTION

Geomorphological field investigations were conducted for HDR, Sioux Falls, South Dakota, on behalf of the National Park Service for the Effigy Mounds National Monument on September 14 and 15, 2020. The investigation was conducted in the Yellow River Valley a short distance from the Mississippi River near Marquette, Iowa (Figure 1). The project area lies on a complex set of landform sediment assemblages (LSAs) including Holocene alluvial fans, and colluvial slopes. Below the Holocene deposits lies the remnant of the Savanna terrace with glacial Lake Superior red clay, and grey silt/clay from western sources up the ancestral late glacial Minnesota River valley.

Most of the project area contained variable amount of fill material at the surface with few areas remaining undisturbed. The most significant disturbance has occurred along the eastern end of the project area near the visitor center. Some locations contain historical sediment deposits below the fill material, while other locations had historical deposits imbedded in the fill material.

The geomorphological work was to determine what landforms lie below the disturbed surface material and determine if cultural potential exists below the fill and into native soils. Giddings probe (GP) cores were advanced along two east-west transects in order to examine the soils. The first southern transect included GPs 1–7, and the second northern transect included GPs 8–15 (Figure 2). The first southern transect lies on an alluvial fan/terrace complex, while the second northern transect lies along a colluvial slope. In addition, two sampling tube cores were advanced along the western portion of the project area.

Based on the geomorphological investigations buried pre-contact cultural potential exists below the surface disturbance in the buried native surface soil and lower paleosols.

However, in nearly all cases, the buried native soil has been disturbed. Generally, the further west along the two transects, the less disturbance occurred in the native soil.

METHODS

Field investigation

The first step in the investigation process began with a Google Earth review of the project area and a review of the Prairie du Chien topographic quadrangle map. The next phase was an on-site geomorphological assessment that included coring using Giddings probe core and sampling tube core methods.

The geomorphological investigation included advancement of Giddings probe cores approximately 5 and 7.5 cm in diameter and approximately 120 cm long, and of sampling tube cores, with a diameter of approximately 2 cm and a tube length of approximately 40

cm. Coring was conducted at 17 locations along the project corridor. The depth of the cores varied from about 30–740 cm deep.

The soil core descriptions included color, texture, structure, consistence, sorting, special features (roots, pores, voids, mottling, gleying, silica and/or carbonate coatings, krotovinas, concretions, organics, clay skins) effervescence, and horizon boundary. Colors of the deposits were determined with a Munsell color chart. Soil reaction where applicable was determined through application of a weak 10% hydrochloric acid solution. Vegetation, depth to the water table (if encountered), and total core depth were recorded at each location.

The profiles were described according to taxonomic nomenclature normally used for Midwest Quaternary studies. Photographic documentation of the investigations was conducted using a Nikon D90 digital SLR camera. Locations of the cores were determined with a hand-held Garmin Etrex GPS unit using NAD83. Elevation was estimated using Google Earth. The reader is encouraged to review the detailed soil profile descriptions in the appendix of this report.

The following section provides a brief landscape evolution overview and summary of the detailed soil descriptions and observations conducted during the geomorphological field investigation.

Overview

The discharges from glacial lakes that formed occurred between 13,000 and 9500 B.P. were the sources of slack water conditions necessary for the deposition of fine-grained sediment (Clayton and Moran 1982). The red clay is believed to have come from glacial Lake Superior sources, while the gray silt/clay is believed to have come from sources farther west. Large-scale flood events from glacial Lakes Agassiz, Grantsburg, and Superior were probably the main contributors of the sediments (Flock 1983). Meltwater containing red clay from glacial Lake Superior drained through the St. Croix River valley and into the Mississippi River valley. While to the west, glacial lakes containing grey silt/clay discharged through the late glacial ancestral Minnesota River valley and into the Mississippi.

The Mississippi River continued to aggrade until the Red River and Superior lobes retreated north approximately 12,200 B.P. (Clayton 1982). As the lobes retreated, rapid incision occurred creating the Savanna terrace, and by 11,500 B.P. both the Red River and Superior lobes readvanced causing renewed aggradation. This event was followed by subsequent valley incision until about 10,800 B.P. The final episode of valley entrenchment occurred when glacial advances blocked the eastward drainage of Lake Superior causing the discharge of meltwater through the Mississippi Valley from 9900– 9500 B.P.

The older and higher Savanna terrace lies about 10–15 m (32.8–49.25 ft) above the valley floor, while the younger lower Kingston terrace lies from 3–5 m (9.8–16.4 ft) above the valley floor. Both lie above the younger early to mid-Holocene Mississippi River main valley surfaces. These terraces contain glacial lake red clay and grey silt/clay deposits in their sedimentological suites (Anderson 2004; Bettis and Anderson 1996; Hajic et al 2006).

A similar terrace is observed in Mississippi River Pool 7 upstream of La Crescent, Minnesota, along Dakota Creek on the Minnesota side of the valley (Anderson 1987).

During the early Holocene, valley alluviation including alluvial fan development appears to have been proceeding in many parts of the Midwest (Knox 1972, 1976). Persistent dry conditions from 9500–4700 B.P. occurred in east central Minnesota (Forester et al. 1987;

Webb and Bryson 1972). For example, in the Des Moines and Iowa River valleys, alluvial fan development progressed throughout the early and middle Holocene with stabilization occurring about 4,000 years ago (Anderson 1988; Benn and Bettis 1985; Bettis 1986).

The persistent dry conditions favored eolian activity (Ketz and Anderson 1995) and hillslope erosion, which promoted the development of valley margin alluvial fans and colluvial slopes. As climate became slightly cooler and wetter around 4700 B.P., the local response was more hillslope stabilization and reduced hillslope erosion. However, localized episodes of hillslope erosion and eolian activity have persisted into the historic period.

A recent geoarchaeological study was conducted by Artz (2018) close to the current project area but to the south and east. The results showed surface disturbance and below late Woodfordian Savanna terrace deposits. The cores during the geoarcheological investigation continued to a depth of 200 cm for the first six cores and to 150 cm for the remaining 10 cores.

Field Results

The project area has been highly disturbed from periods of national park development.

Parking lot and visitor center development has caused regrading of the surface and disturbance into the native soils. As a result, the surface contains fill material of gravelly silt.

Two east-west Giddings probe transects occurred across the project area. The first southern transect included GPs 1–7, and the second northern transect included GPs 8–15. The first southern transect lies on an alluvial fan/terrace complex, while the second northern transect lies along a colluvial slope. The location of the sampling tube cores, and Giddings probe cores can be found on Figure 2. Geologic cross sections A-A’, and B-B’ characterize the deposits found along the two transects (Figures 3 and 4).

Southern Giddings Probe Transect GPs 1–7 Cross Section A-A’

Fill material on the surface ranges from about 60–125 cm thick along the southern transect.

The fill is poorly sorted, gravelly silt sediment with calcareous limestone clasts. Below the fill lies native soils with varying degree of disturbance. For example, GPs 2 and 3 show disturbed, very thin native A horizons, while GPs 4–7 show better preserved native A horizons.

The native soils are well drained and developed in locally derived mid- to late Holocene alluvial fan deposits from GPs 1–6. A paleosol is observed below the mid- to late fan deposit at GP6 and is developed in early to mid-Holocene fan deposits. In addition, the native soil in GP7 is developed in early to mid-Holocene fan deposits. These native soils and paleosol are generally leached of carbonates, and the older early to mid-Holocene fan deposits show a clay enriched, argillic Bt horizon indicative of landscape stability and soil development for at least a few to several thousand years.

The basal deposits observed along cross section A-A’ are late Woodfordian Savanna terrace deposits. These deposits are thin bedded, strongly calcareous laminae of silt and clay, and are Mississippi River main valley alluvium derived from late Woodfordian glacial lake discharges.

The exception along the transect occurs at GP1. At this location, there appears to be a calcareous, poorly drained deposit of very late Holocene to historic aged alluvial fan deposit below the fill. Below this recent deposit lies a paleosol developed in poorly drained late Holocene non-calcareous fan deposits.

Northern Giddings Probe Transect GPs 8–15, Cross Section B-B’

Along this transect the fill material on the surface ranges from about 30–180 cm thick (Table 1). The fill is poorly sorted, gravelly silt with calcareous limestone clasts, and in some cases is mixed with historical hillslope alluvium/colluvium. The only definite artifact recovered in the soil cores is a flake within the lower portion of the fill in GP5.

Below the fill in GPs 12 and 13 lies calcareous recent historical hillslope alluvium/ colluvium. In GPs 10 and 11, very late Holocene to historic-age hillslope alluvium/ colluvium is observed below the fill. GP12 shows very late Holocene to historical alluvium/colluvium below the fill and recent historical alluvium/colluvium. Non-calcareous late Holocene alluvium/colluvium is observed below the fill in GP8, while GP9 showed a non-calcareous early to mid-Holocene deposit below the fill. A late Holocene soil observed in GP6 at 125–155 cm (directly below fill) might be a mound remnant.

The early to mid-Holocene deposit is observed across most of the cross section. The exceptions are where refusal from coarse colluvium or from gravelly silt fill prevented deeper core penetration. A paleosol occurs at the top of the early to mid-Holocene deposit (GP8) and it shows a clay enriched, argillic Bt horizon and is leached of carbonates.

The basal deposits seen along the transect are Mississippi River derived late glacial alluvium. Superior red clay and ancestral late glacial Minnesota River derived grey silt occurs deep in the cores. The calcareous deposits comprise the Savanna terrace landform sediment assemblage and are late Woodfordian-age.

Sampling Tube Cores STs 1 and 2

Two sampling tube (ST) cores were advanced west of the transects, the first along a colluvial slope and the second at a location where a building previously stood. At the colluvial slope, the first three cores at ST1 met refusal at around 30 cm from coarse colluvium. The fourth core showed a profile developed in late Holocene colluvium and met refusal at 185 cm. ST2 showed refusal from brick building material at 100 cm.

DISCUSSION

The basal deposits across the project area are main Mississippi River valley alluvium composed of calcareous silt and clay derived from further upstream in the drainage system.

They constitute the Savanna terrace landform sediment assemblage and result from valley aggradation followed by periods of catastrophic glacial lake discharges during the final stages of Wisconsinan glaciation. Following the aggradational episodes accumulating sediments in the valley, erosional episodes of valley incision of about 10–15 m (32.8–49.2

ft) occurred leaving prominent terraces along the Mississippi River valley margin and up into the tributary valleys. In the cross sections these deposits are observed between about 200–202 cm.

Following deep valley entrenchment around 9500 B.P., periods of valley alluviation episodically occurred throughout the Holocene and into the historic period. Periods of landscape stability and soil development occurred and is observed in the paleosols observed in the cores. A major period of hillslope erosion and deposition occurred during the early to mid-Holocene. These hillslope deposits capped the Savanna terrace.

Landscape stability ensued for a significant period of time, for more than a few thousand years to leach out carbonates and developed clay enriched Bt horizons.

Later, periods of valley alluviation occurred during the mid- to late Holocene, as these deposits generally overlie the older Holocene deposits (Table 1). This is best observed in cross section A-A’ where mid- to late Holocene alluvial fan deposits overlie the older early to mid-Holocene fan deposits.

The final increment of hillslope alluvium and colluvium has occurred during the historic period. These deposits are best observed along the valley margin transect cross section B- B’. Recently, regrading of the surface near the parking lot and visitor center has seriously affected the native soils across the project area. Native soils near the visitor center are most affected compared to areas further away and to the west of the center.

CONCLUSION

Geomorphological investigations were conducted for HDR on behalf of the National Park Service at the Effigy Mounds National Monument during September 2020. The investigation was conducted near the mouth of the Yellow River valley a short distance from the Mississippi River. A complex set of LSAs occur along the project area including Holocene alluvial fans, and colluvial slopes. Underlying the Holocene deposits lies the remnant of the Savanna terrace with glacial Lake Superior red clay and grey silt/clay derived from sources west in the late glacial ancestral Minnesota River valley.

Across the project area variable thicknesses of recent fill material is observed. The fill varies in thickness and the underlying native soil has been affected to varying degrees. At two locations along the northern transect (GPs 14 and 15), the fill could not be penetrated, and wetland soils were observed at GP1.

Based on the geomorphological investigations buried pre-contact cultural potential exists below the surface disturbance in the buried native surface soil and lower paleosols.

However, in nearly all cases, the surface of the buried native soil has been disturbed.

Generally, the further west along the transect, the less disturbance occurred in the native soil. Although the surface of the upper buried soil is often disturbed, the underlying horizons are generally intact and a lower Holocene-age soil is frequently present.

Therefore, the potential for pre-contact cultural deposits below the fill within this project area is considered to be high for much of the project area.

REFERENCES CITIED

Anderson, Jeffrey D.

1987 Geomorphic Mapping Pool 7 - Upper Mississippi River Basin. Donohue &

Associates, Inc., Sheboygan, Wisconsin.

1988 Holocene Landscape Evolution In The Iowa River Valley: Coralville Reservoir, Iowa. Master's thesis, University of Wisconsin-Madison.

2004 Geomorphological test Excavations Locational Database, Upper Mississippi

River Floodplain in St. Louis (MVS), Rock Island (MVR), and St. Paul Districts (MVP). Revised February 2017. CRM 1270. American Resources Group, Ltd, Carbondale, Illinois.

Artz, Joe Alan 2018 Phase I Geoarchaeological Survey Effigy Mounds National Monument, Replace

Critical Septic Systems at the Visitor Center and Maintenance/Office Area, Allamakee County, Iowa. EarthView Environmental, Coralville, Iowa, and Louis Berger, Kansas City, Missouri.

Benn, David W., and E. Arthur Bettis III 1985 Archaeology and Landscapes in Saylorville Lake, Iowa. Field Trip Guidebook for the Association of Iowa Archaeologists Annual Summer Meeting. Southwest Missouri State University, Springfield.

Bettis, E. Arthur, III 1986 Late Wisconsinan and Holocene Landscape Evolution and Alluvial Stratigraphy in the Saylorville Lake Area, Central Des Moines River Valley, Iowa. Report 86-1.

Geological Survey Bureau, Iowa Department of Natural Resources, Iowa City.

Bettis E. Arthur, III, and Jeffrey D. Anderson 1996 Explanatory Text Accompanying Landform Sediment Assemblage Maps for the

Mississippi River Valley within the Rock Island District, Illinois, Iowa, Missouri, and Wisconsin. Vol. 1 and 2. Technical Report No. 95-1004-11b. Illinois State Museum Research and Collections Center, Quaternary Studies Program, Springfield.

Birkeland, P. W.

1999 Soils and Geomorphology. Oxford University Press, New York.

Clayton, Lee 1982 Influence of Aggassiz and Superior Drainage on the Mississippi River. In:

Quaternary History of The Driftless Area-Field Trip Guidebook Number 5. Pages 83–

87. Geological and Natural History Survey, Madison.

Clayton, Lee, and S. R. Moran 1982 Chronology of Late Wisconsinan Glaciation in Middle North America.

Quaternary Science Review 1:55–82.

Flock, Mark A.

1983 The Late Wisconsin Savanna Terrace in Tributaries to the Upper Mississippi

River. Quaternary Research 20:165–176.

Forester R. M, L. D. Delorme, and J. P. Bradbury 1987 Mid-Holocene Climate in northern Minnesota. Quaternary Research 28:263–

273.

Hajic, E. R., D. W. Benn, J. D. Anderson, and E. A. Bettis III 2006 Landform Sediment Assemblage Maps for the Mississippi River Miles 125-260

Within the St. Louis District. BCA 1281. Bear Creek Archeology, Cresco, Iowa.

Ketz, Anne, and Jeffrey D. Anderson 1995 Phase I Survey for the TH49 and CSAH23 and Phase II Evaluations for Sites

21AN30 (Skink Site) and 21AN75 (Pocket Gopher Site), Lino Lakes, Anoka County, Minnesota. The 106 Group, Ltd, St. Paul.

Knox, J. C.

1972 Valley Alluviation in Southwestern Wisconsin. Annals of the Association of

American Geographers 62:401–410.

1976 Impact of Fluvial erosion on the Great Plains Altithermal Cultural Hiatus.

Symposium: Anthropology on the Great Plains: The State of the Art. Joint Plains- Midwest Anthropological Conference, Minneapolis.

Lee, Gerhard B.

1981 Soil Morphology, Classification and Mapping. Soil Science, University of

Wisconsin-Madison.

Soil Survey Staff 1975 Soil Taxanomy. USDA Handbook 436, U.S. Government Printing Office, Washington, DC.

1993 Soil Survey Manual. USDS Handbook 18, U.S. Government Printing Office, Washington, DC.

Webb, Thompson, III, and R. A. Bryson 1972 Late and Postglacial Climatic Change in the Northern Midwest, USA.

Quantitative Estimates Derived from Fossil Pollen Spectra by Multivariate Statistical Analysis. Quaternary Research 2:70–115.

TABLES

Table 1. Soil profile summary.

Probe Surface Fill

Depth

Native Soil Depth to C horizon

Archeological Potential

GP1 80 cm 80–250 cm: very late Holocene to historic;

205–290 cm: mid to late Holocene

Holocene: 240 cm Low, wetland soils

GP2 110 cm 110–200 cm: mid to late Holocene Holocene: 170 cm;

Savanna: 200 cm

Low, truncated

GP3 90 cm 90–280 cm: mid to late Holocene Holocene: 210 cm;

Savanna: 280 cm

High, but native surface is disturbed

GP4 100 cm 100–245 cm: mid to late Holocene Holocene: 205 cm;

Savanna: 245 cm

High

GP5 110 cm 110–210 cm: mid to late Holocene Savanna: 215 cm High, flake in lower portion of fill & possible shatter in AEb horizon--130 cm

GP6 125 cm 125–155 cm: late Holocene;

155–315 cm: early to mid Holocene

Savanna: 315 cm High, possible mound remnant 125–155 cm (late Holocene soil)

GP7 60 cm 60–250 cm: early to mid Holocene Savanna: 250 cm High

GP8 70 cm 70–135 cm: late Holocene;

135–260 cm: early to mid Holocene

Holocene: 250 cm;

Bedrock: 260 cm

High, but late Holocene surface is disturbed

GP9 65 cm 65–225 cm: early to mid Holocene None;

Bedrock: 225 cm

GP10 0 cm 0–30 cm: recent;

30–105 cm: late Holocene to historic

Holocene or historic: 80 cm

Low

GP11 40 cm 0–40 cm historic sediment mixed with fill;

40–100 cm: late Holocene to historic

Holocene or historic: 70 cm

Low

GP12 70 cm 70–185 cm: historic to recent;

185–320 cm: late Holocene to historic;

320–500 cm: early to mid Holocene;

500–660 cm: early Holocene

Holocene: 520 cm;

Savanna: 660 cm

GP13 80 cm 80–180 cm: historic;

180–385 cm: early to mid Holocene

Holocene: 335 cm;

Savanna: 385 cm

GP14 120 cm All fill All fill Unknown, fill could not be penetrated

GP15 130 cm All fill All fill Unknown, fill could

ST1 0 cm 0–185 cm: late Holocene none Moderate

ST2 100 cm All fill All fill Unknown, fill could

FIGURES

-Project Area (BCA #2780)

610 m

2000 ft

1:24000

Figure 1. Topographic coverage of the project area.

USGS 7.5' Quad Prairie Du Chien, WI-IA (1983)

Allamakee Co.

T96N, R3W

Project Area

-Giddings Probe (GP#) -Sampling Tube (ST#)

Figure 2. Scale map of the coring locations.

30 m

100 ft

1:1200

ST1ST1

ST2ST2

GP9GP9

GP8GP8

GP7GP7

GP6GP6

GP5GP5

GP4GP4

GP3GP3 GP2GP2 GP1GP1

GP15GP15GP13GP13

GP12GP12

GP11GP11GP10GP10

IOWA 76

IOWA 76

Parking Lot Parking Lot

Parking LotParking Lot Admin Building

Maintenance Building

Natural Resources Building Visitors Center

GP14GP14

E le v a ti o n i n M e te rs A

M S

L (V e rt ic a l E x a g g e ra ti o n x

-Unknown Boundary

? -Potential Boundary

-Water Table

-Paleosol

-Bottom of Borehole

-Gravelly Silt Fill

Early to Mid Holocene Alluvial Fan Deposits

A

Ab

Clayey Silt

Non Calcareous

Ab

Ab2

Clayey Silt

Non Calcareous

Bwb

AbSilt

Gravelly Silt Fill

Silt

Non Calcareous

Silt Thin Bedded

Strongly Calcareous

2Cb2

Clayey Silt

Strongly Calcareous

Thin Bedded Alluvium

Late Woodfordian Main Valley Alluvium

Ab

Ab

Bwb Silt

Silt

Non Calcareous Bwb

Slightly Calcareous

2Cb

Strongly Calcareous

Thin Bedded Alluvium

Strongly Calcareous

Gravelly Silt Fill

AbSilt

BCb

Slightly Calcareous

Strongly Calcareous 2C2b

Clayey Silt Thin Bedded

Alluvium

2C3b

Ab

Slightly Calcareous

Cgb

Poorly Drained

Ab2

Non Calcareous

Cgb2

10080 Horizontal Distance in Meters

40 600 20

A’

Mid to Late Holocene Alluvial Fan Deposits

Very Late Holocene to Historic Alluvial

Fan Deposits

Effigy Mounds National Monument Geologic Cross Section A-A’

2Cb

Silt

Btb

2Cb

2Cb Btb2 GP2

GP3

GP1

GP5

GP6

GP7

GP4

Figure 3. Southern Giddings Probe transect cross section A-A’.

GP13

GP9

1008040 600 20

Cherty Colluvium

Refusal

Late Holocene Hillslope Alluvium/ Colluvium

Strongly Calcareous

Non Calcareous Ab Ab

Non Calcareous

Ab2

Clayey Silt

Btb2

Non Calcareous

A

BC Silt

Cherty Colluvium

Refusal Btb Clayey

Silt

Sandstone Bedrock Refusal

Early to Mid Holocene Hillslope Alluvium/Colluvium

E le v a ti o n i n M e te rs A

M S

L (V e rt ic a l E x a g g e ra ti o n x

Late Woodfordian Main Valley Alluvium

Effigy Mound National Monument Geologic Cross Section B-B’

Very Late Holocene to Historic Hillslope Alluvium/Colluvium

A

Silt

Calcareous

Historical Hillslope Alluvium/Colluvium

Strongly C alcareous

Ab

Silt

Strongly

Calcareous

Silt

Gravelly Silt Fill

Gravelly Silt Fill

Ab

ABtb2

Clayey Silt

Clayey Silt Clayey Silt

Btb2

Btgb

ABb3

Non Calcareous

Non Calcareous

2C2b

Superior Red Clay and Glacial Minnesota River Valley Grey Silt

Superior Red Clay and Glacial Minnesota River Valley Grey Silt

Refusal from

Coarse Gravelly

Fill

Late Woodfordian Main Valley Alluvium

Calcareous

2C4b3

B’B

Horizontal Distance in Meters

GP10GP8

GP11

GP12

GP14

GP15

-Unknown Boundary

? -Potential Boundary

-Water Table

-Paleosol

-Bottom of Borehole

-Gravelly Silt Fill

Figure 4. Northern Giddings Probe transect cross section B-B’.

APPENDIX A

Soil Profiles

Profiles in the report appendix generally follow those used in Soil Survey Staff (1993) and Lee (1981). Buried soil horizons were designated according to procedures used by Birkeland (1999).

The descriptions consider a soil to be buried if there is a surface mantle of new material 50 cm or more thick (Soil Survey Staff 1975). In some cases, the overlying mantle is historical alluvium greater than 50 cm thick and buries the native soil. In these cases, the native soil gets the Ab, but is not recognized as a paleosol. The first buried soil is designated with the subscript “b” (Ab or Ab1), and additional buried soils receive a numerical designation following the “b” subscript (Ab2). Furthermore, each different geological unit is noted by an Arabic numeral prefix. The numerals precede the master horizon designation and the numeral for the uppermost layer is omitted. For example, an A horizon in loess over a Bt horizon in till would receive a designation “A-2Bt”. Elevations are estimated from Google Earth.

PROBE NAME: GP1

GEOMORPHIC SURFACE: disturbed Holocene terrace/fan complex POSITION IN LANDSCAPE: flat lying PARENT MATERIALS: graded fill and fine-grained alluvium WATER TABLE: below bottom of core

SLOPE: 0–2%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 90 cm, then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 290 cm APPROXIMATE UTM LOCATION: 4772265, 647635 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 200.3 m, 657’ +/- 3’ PHOTOGRAPHS: A1-location, A2-profile, A3-upper portion, A4-Ab2 contact and below

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill, and below lies historical/very late Holocene alluvium, then fine-grained mid- to late Holocene alluvium. The native soils are wetland soils and begin at 205 cm.

Depth (cm) Soil Horizon Description 0–80 C 10YR 3/3; gravelly silt fill (0-40 cm); massive; friable; 10YR 4/1 silt (40-60 cm) massive; friable; 10YR 5/4 silt (60-80 cm); massive; friable; few fine roots; units of graded fill show abrupt contacts; moderately to violently effervescent; abrupt boundary.

80–100 Ab 10YR 3/1; silt loam; massive; friable; few fine roots; historical to very late Holocen alluvium; slightly effervescent; abrupt boundary.

100–140 Cgb 10YR 4/1; silt loam; massive; friable; common medium distinct mottles; slightly effervescent; clear boundary.

140–205 Cg2b 10YR 4/1; silt loam; massive; friable; common medium distinct mottles; slightly

205–240 Ab2 10YR 3/2–10YR 2/2; silt loam; weak medium subangular blocky; friable; common fine root and worm holes; noneffervescent; clear boundary.

240–260 Cg2b2 N3/0; silt loam; massive; sticky; noneffervescent; clear boundary.

260–290 Cg4b2 10YR 4/1; silty clay loam to silty clay; massive; sticky; many medium faint mottles;

noneffervescent. End.

SITE NAME: GP2

GEOMORPHIC SURFACE: disturbed Holocene terrace/fan complex POSITION IN LANDSCAPE: flat lying PARENT MATERIALS: graded fill over silt and clay alluvium WATER TABLE: below bottom of core

SLOPE: 0–2%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 1.10 m (3.6 ft), then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 330 cm APPROXIMATE UTM LOCATION: 4772269, 647615 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 201.1 m, 660’ +/- 3’ PHOTOGRAPHS: A5-profile, A6-upper portion, A7-lower portion

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill, and below lies truncated native mid- to late Holocene silty soils that become clayey at the base of the profile. What remains of a very thin native A horizon is observed from 110–115 cm. Main valley alluvium appears at the base of the profile.

0–110 C 10YR 2/2; gravelly silt fill and 10YR 3/3 and 10YR 4/4 silt fill with few carbonate clasts; massive; friable and firm; units of graded fill; few coarse distinct mottles at base of horizon; moderately to violently effervescent; abrupt boundary.

110–115 Ab 10YR 3/110YR 3/2; silt loam; massive; friable; few fine roots; heavily disturbed and truncated native A horizon; slightly effervescent; abrupt boundary.

115–170 BCb 7.5YR 5/6; silt loam; weak medium subangular blocky; friable; common fine root and worm holes; many medium distinct mottles; slightly effervescent; clear

170–200 Cb 10YR 5/6; silt loam; weak medium subangular blocky to massive; friable; few fine root and worm holes; common medium distinct mottles; slightly effervescent; clear

200–300 2C2b 10YR 5/6; silt loam; massive; friable; few fine carbonate concretions; violently effervescent; abrupt boundary

300–330 2C3b 10YR 4/3; silty clay loam to silty clay; massive; sticky; thin bedded alluvium; many coarse distinct mottles and carbonate accumulations along bedding planes; violently effervescent. End.

SITE NAME: GP3

POSITION IN LANDSCAPE: flat lying PARENT MATERIALS: graded fill over silty alluvium WATER TABLE: below bottom of core

SLOPE: 0–2%

VEGETATION: grass METHODOLOGY: Giddings probe 3” core to about 1.70 m (5.6 ft), then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 310 cm APPROXIMATE UTM LOCATION: 4772262, 647593 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 202.1 m, 663’ +/- 3’ PHOTOGRAPHS: A8-profile, A9-profile at 45–140 cm, A10-profile at 120–200 cm, A11-profile at 275–310 cm

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill, and below lies truncated native mid to late Holocene silty soil. What remains of a very thin native A horizon is observed from 90–100 cm.

Main valley alluvium appears at the base of the profile.

0–90 C 10YR 2/2; gravelly silt fill and 10YR 3/3 and 10YR 4/4 silt fill with few carbonate clasts; massive; friable and firm; units of graded fill; moderately to violently effervescent; abrupt boundary.

90–100 Ab 10YR 2/2; silt loam; moderate medium subangular blocky breaking to moderate medium granular; friable; common fine root and worm holes; noneffervescent; clear

100–130 AEb 10YR 4/2; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; noneffervescent; clear boundary.

130–160 Bwb 7.5YR 4/6; silt loam; weak medium subangular blocky; friable; many fine root and worm holes; few white silans along ped faces; noneffervescent; clear boundary.

160–210 BCb 7.5YR 4/6; silt loam; weak medium subangular blocky; friable; common fine root and worm holes; noneffervescent; gradual boundary.

210–280 Cb 10YR 4/3; silt loam; massive; sticky; common medium distinct mottles; slightly

280–310 2C2b 10YR 4/4; silt loam; massive; sticky; thin bedded alluvium; common medium distinct mottles and white carbonate accumulations along bedding planes; violently

SITE NAME: GP4

POSITION IN LANDSCAPE: flat lying PARENT MATERIALS: graded fill over silty alluvium WATER TABLE: below bottom of core

SLOPE: 0–2%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 1.60 m (5.2 ft), then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 275 cm APPROXIMATE UTM LOCATION: 4772260, 647579 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 202.4 m, 664’ +/- 3’ PHOTOGRAPHS: A12-profile, A13-upper portion, A14-lower portion

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill to about 100 cm and below lies a native mid- to late Holocene silty soil. Main valley alluvium appears at the base of the profile.

0–100 C 10YR 2/2; gravelly silt fill and 10YR 3/3 and 10YR 4/4 silt fill with few carbonate

100–130 Ab 10YR 2/3; silt loam; moderate medium subangular blocky; friable; many fine root

130–140 AEb 10YR 4/2; silt loam; moderate medium subangular blocky; friable; many fine root

140–185 Bwb 10YR 4/4; silt loam; weak medium subangular blocky; friable; many fine root and worm holes; common medium distinct mottles; noneffervescent; clear boundary.

185–205 BCb 10YR 5/4; silt loam; weak medium subangular blocky; friable; common fine root and worm holes; common medium distinct mottles; noneffervescent; gradual

205–245 Cb 10YR 4/4; silt loam; massive; friable; common medium distinct mottles; slightly

245–275 2C2b 10YR 4/4; silt loam; massive; sticky; thin bedded alluvium; common medium distinct mottles and white carbonate accumulations along bedding planes; violently

SITE NAME: GP5

POSITION IN LANDSCAPE: flat lying PARENT MATERIALS: graded fill over silty alluvium WATER TABLE: 240 cm

SLOPE: 0–2%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 1.05 m (3.4 ft), then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 265 cm APPROXIMATE UTM LOCATION: 4772256, 647560 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 203.6 m, 667’ +/- 3’ PHOTOGRAPHS: A15-profile, A16-contact with Ab horizon

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill to about 110 cm and below lies a native mid- to late Holocene silty soil. At 90–100 cm, yielded a small pressure flake and a possible piece of shatter; both are made from locally available Prairie du Chien chert. The core also yielded 8– 10 very small pieces/bits of carbonized wood. An angular chert possibly cultural found at 130 cm.

Main valley alluvium appears at the base of the profile.

0–110 C 10YR 2/2; gravelly silt fill and 10YR 3/3 and 10YR 4/4 silt fill with few carbonate

110–130 Ab 10YR 3/2; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; few medium distinct mottles; angular chert at base of horizon;

noneffervescent; clear boundary.

130–145 AEb 10YR 4/2; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; common medium distinct mottles; noneffervescent; clear boundary.

145–165 Bwb 7.5YR 4/6; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; common to many medium distinct mottles; slightly effervescent;

clear boundary.

165–210 BCb 10YR 4/4; silt loam; weak medium subangular blocky; friable; common fine root and worm holes; common medium distinct mottles; moderately effervescent; gradual

210–265 2Cb 10YR 4/3; silt loam; massive; sticky and becoming saturated; thin bedded alluvium;

few to common medium faint mottles; violently effervescent. End.

SITE NAME: GP6

POSITION IN LANDSCAPE: flat lying PARENT MATERIALS: graded fill over silty alluvium WATER TABLE: below bottom of core

SLOPE: 0–2%

VEGETATION: grass and maple tree METHODOLOGY: Giddings Probe 3” core to about 60 cm, then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 340 cm APPROXIMATE UTM LOCATION: 4772250, 647549 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 203.6 m, 668’ +/- 3’ PHOTOGRAPHS: A17-profile, A18-Ab horizon area, A19-Ab2 horizon area, A20-base

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill to about 125 cm and below lies a native soil. There appears to be a late to very late Holocene soil below the fill which could possibly be a mound remnant. An additional buried early to mid-Holocene soil lies below. Main valley alluvium appears at the base of the profile.

0–125 C 10YR 2/2; gravelly silt fill and 10YR 3/3 and 10YR 4/4 silt fill with few carbonate

125–140 Ab 10YR 2/2; silt loam; moderate medium subangular blocky breaking to moderate medium granular; friable; many fine root and worm holes; noneffervescent; clear boundary

140–155 AEb 10YR 2/3; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; common white silans on ped faces; noneffervescent; clear

155–180 Ab2 10YR 2/2; silt loam; moderate medium subangular blocky breaking to moderate

180–240 AEb2 10YR 3/2; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; common white silans on ped faces; noneffervescent; clear

240–275 Btb2 10YR 4/3; silty clay loam; moderate medium subangular blocky; friable; many fine root and worm holes; common 10YR 3/3 argillans; noneffervescent; clear

275–315 BCb2 10YR 4/4; silty clay loam; weak medium subangular blocky; firm; common fine root and worm holes; few medium distinct mottles; slightly effervescent; gradual

315–340 2Cb2 10YR 4/4; silt loam to silty clay loam; massive; friable; moderately effervescent.

End.

SITE NAME: GP7

POSITION IN LANDSCAPE: flat lying PARENT MATERIALS: graded fill over silty alluvium WATER TABLE: below bottom of core

SLOPE: 0–2%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 90 cm, then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 325 cm APPROXIMATE UTM LOCATION: 4772236, 647535 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 203.9 m, 669’ +/- 3’ PHOTOGRAPHS: A21-profile, A22-A horizon below the fill

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill and below lies a native soil. The native soil is developed in early to mid-Holocene silty alluvium. Main valley alluvium appears at the base of the profile.

0–60 C 10YR 2/2; gravelly silt fill and 10YR 3/3 and 10YR 4/4 silt fill with few carbonate

60–100 Ab 10YR 2/1; silt loam; moderate medium subangular blocky breaking to moderate

100–150 AEb 10YR 3/2; silt loam; weak medium subangular blocky; friable; many fine root and worm holes; perched water table saturated no white silans; noneffervescent; clear

150–215 Btb 10YR 4/4; silty clay loam; moderate medium subangular blocky; friable; many fine root and worm holes; common 10YR 3/3 argillans; noneffervescent; clear boundary.

215–250 BCb 10YR 4/4; silt loam; weak medium subangular blocky; friable; few fine root and worm holes; few medium faint mottles; slightly effervescent; gradual boundary.

250–325 2Cb 10YR 4/4; silt loam; massive; friable; few carbonate lenses along thin bedded alluvial laminae; violently effervescent. End.

SITE NAME: GP8

GEOMORPHIC SURFACE: disturbed Holocene colluvial slope POSITION IN LANDSCAPE: flat lying near channelized drainage along valley wall PARENT MATERIALS: graded fill over silty alluvium/colluvium WATER TABLE: below bottom of core

SLOPE: 2–5%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 200 cm, then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 265 cm APPROXIMATE UTM LOCATION: 4772278, 647545 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 209.1 m, 686’ +/- 5’ PHOTOGRAPHS: A23-profile, A24-middle of profile Ab2 horizon, A25-base of profile sandstone bedrock refusal

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill and below lies a native soil developed in late to very late hillslope alluvium/colluvium. Below lies a paleosol developed in early to mid- Holocene alluvium/colluvium. Chert clast at 90 cm.

0–70 C 10YR 2/2; gravelly silt fill and 10YR 3/3 gravelly silt fill; massive; friable and firm;

units of graded fill; moderately to violently effervescent; abrupt boundary.

70–80 Ap 10YR 2/1; silt loam; weak coarse angular blocky; friable to firm; many fine root and worm holes; noneffervescent; clear boundary.

80–115 Ab 10YR 2/1; silt loam; moderate medium granular; friable; many fine root and worm holes; chert clast at 90 cm; noneffervescent; clear boundary.

115–135 ABb 10YR 2/2–10YR 2/3; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; noneffervescent; clear boundary.

135–145 Ab2 10YR 2/2; silt loam; moderate medium subangular blocky breaking to moderate

145–160 ABb2 10YR 2/3; silt loam; moderate medium subangular blocky; friable; many fine root and worm holes; noneffervescent; clear boundary.

160–210 Btb2 10YR 3/3; silty clay loam; moderate medium subangular blocky; friable; many fine root and worm holes; common 10YR 2/3 argillans; noneffervescent; clear boundary.

210–250 BCb2 10YR 4/4; silt loam; weak medium subangular blocky; friable; common fine root and worm holes; slightly effervescent; clear boundary.

250–260 Cb2 10YR 5/4; silt loam; massive; friable; slightly effervescent; abrupt boundary.

260–265 R Sandstone bedrock refusal. End.

SITE NAME: GP9

POSITION IN LANDSCAPE: flat lying near channelized drainage along valley wall PARENT MATERIALS: graded fill over silty alluvium/colluvium WATER TABLE: below bottom of core

SLOPE: 2–5%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 90 cm, then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 230 cm APPROXIMATE UTM LOCATION: 4772263, 647532 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 209.1 m, 686’ +/- 5’ PHOTOGRAPHS: A26-profile, A27-upper portion, A28-lower portion

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill and below lies a native soil developed in early to mid-Holocene alluvium/colluvium.

0–65 C 10YR 2/2–10YR 2/1; gravelly silt fill; weak coarse subangular blocky; friable and firm; units of graded fill; moderately to violently effervescent; abrupt boundary.

65–95 Ab 10YR 2/1; silt loam; moderate medium granular; friable; many fine root and worm holes; noneffervescent; clear boundary.

95–155 ABb 10YR 2/2; silt loam; moderate medium and coarse columnar; friable; many fine root

155–185 Btb 10YR 3/3; silty clay loam; strong medium subangular blocky; firm; many fine root and worm holes; common 10YR 2/2 argillans; noneffervescent; clear boundary.

185–225 Bt2b 10YR 4/4; silty clay loam; strong medium subangular blocky; firm; many fine root and worm holes; common 10YR 2/2 argillans; noneffervescent; clear boundary.

225–230 R Sandstone bedrock refusal. End.

SITE NAME: GP10

POSITION IN LANDSCAPE: flat lying near channelized drainage along valley wall PARENT MATERIALS: historical hillslope alluvium over silty alluvium/colluvium WATER TABLE: below bottom of core

SLOPE: 2–5%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 105 cm DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 105 cm APPROXIMATE UTM LOCATION: 4772283, 647570 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 209.1 m, 686’ +/- 5’ PHOTOGRAPHS: A29-profile

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by 30 cm of recent silty historical hillslope alluvium with carbonates and fill. Below lies a weak soil developed in very late Holocene to historic alluvium/colluvium. Refusal from coarse cherty colluvium occurred at 105 cm.

0–30 C 10YR 2/2; silt loam; massive; friable; historical hillslope alluvium; moderately

30–40 A 10YR 2/2; silt loam; moderate medium granular; friable; many fine root and worm holes; few coarse cherty clasts; moderately effervescent; clear boundary.

40–80 BC 10YR 3/3; silt loam; weak medium subangular blocky to massive; friable; many fine root and worm holes; black 10YR 2/2 coatings down root and worm holes; large pebble sized angular chert clast; moderately effervescent; clear boundary.

80–105 C 10YR 3/4; gravelly silt; massive; friable; moderately effervescent; refusal from cherty gravel. End.

SITE NAME: GP11

POSITION IN LANDSCAPE: flat lying near channelized drainage along valley wall PARENT MATERIALS: historical hillslope alluvium over silty alluvium/colluvium WATER TABLE: below bottom of core

SLOPE: 2–5%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 100 cm DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 100 cm APPROXIMATE UTM LOCATION: 4772291, 647587 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 208.2 m, 683’ +/- 5’ PHOTOGRAPHS: A30-profile

DATE DESCRIBED: 9/14/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by 40 cm of recent silty historical hillslope alluvium with carbonates and fill. Below lies a weak soil developed in very late Holocene to historic alluvium/colluvium. Refusal from coarse cherty colluvium occurred at 100 cm.

0–40 C 10YR 2/2; silt loam; massive; friable; fill with historical hillslope alluvium and few limestone chips; moderately effervescent; abrupt boundary.

40–70 A 10YR 2/2; silt loam; moderate medium granular; friable; many fine root and worm holes; few coarse cherty clasts; moderately effervescent; abrupt boundary.

70–100 C 10YR 5/4; silt loam; massive; friable; moderately effervescent; refusal from cherty gravel. End.

SITE NAME: GP12

POSITION IN LANDSCAPE: flat lying near channelized drainage along valley wall PARENT MATERIALS: graded fill over silty alluvium/colluvium, basal Superior red clay and western source gray silt WATER TABLE: 560 cm

SLOPE: 2–5%

VEGETATION: grass METHODOLOGY: Giddings Probe 3” core to about 120 cm, then 2” core DEPTH OF CORE, TRENCH, BORING, OR SOIL PIT: 740 cm APPROXIMATE UTM LOCATION: 4772293, 647605 Zone 15

USGS TOPOGRAPHIC QUADRANGLE: Prairie Du Chien, WI-IA ESTIMATED ELEVATION: 207.3 m, 680’ +/- 5’ PHOTOGRAPHS: A31-profile, A32-upper portion of profile VLH-H Ab horizon, A33-middle portion of profile EMH paleosol begins, A34-lower portion of profile Superior red clay

DATE DESCRIBED: 9/15/2020

DESCRIBED BY: Jeff Anderson PG, CPG REMARKS: The surface is capped by gravelly silt fill and recent historical hillslope alluvium/colluvium. Below lies a very late Holocene to historic aged soil. At 320 cm a paleosol is observed and developed in early to mid-Holocene hillslope alluvium/colluvium. An additional deeper paleosol begins at 500 cm and is developed in early Holocene hillslope alluvium/colluvium.

At the base of the profile lies Glacial Lake Superior red clay and western source gray silt.

0–70 C 10YR 2/2; gravelly silt fill with limestone chips; massive; friable; moderately to violently effervescent; abrupt boundary.

70–185 C2 10YR 5/4; silt loam; massive; friable; historical hillslope alluvium/colluvium;

moderately to violently effervescent; abrupt boundary.

185–240 Ab 10YR 2/2–10YR 3/1; silt loam; weak medium subangular blocky to massive; few fine root and worm holes; faint thin bedded laminae; few medium faint mottles;

slightly effervescent; clear boundary.

240–320 BCgb 10YR 3/1; silt loam; weak medium subangular blocky to massive; faint thin bedded laminae; many medium distinct mottles; slightly effervescent; clear boundary.

320–355 ABtb2 10YR 2/3; silty clay loam; moderate to strong medium and coarse subangular blocky and columnar; firm; common fine root and worm holes, common 10YR 2/1 argillans;

355–420 Btb2 10YR 2/3–10YR 3/3; silty clay loam; strong medium and coarse subangular blocky and columnar; firm; common fine root and worm holes; common 10YR 2/1 argillans;

few medium faint mottles; noneffervescent; clear boundary.

420–500 BCb2 10YR 3/3; silty clay loam; massive; friable; few medium faint mottles;

500–520 ABb3 10YR 2/2; silt loam to silty clay loam; moderate medium subangular blocky; friable;

few fine root and worm holes, common 10YR 2/1 argillans; noneffervescent; clear

520–660 C3b3 10YR 3/3–10YR 4/3; silty clay loam; massive; friable to sticky; common medium faint mottles; noneffervescent; abrupt boundary.

660–720 2C4b3 10R 4/6; silty clay; massive; sticky; Lake Superior red clay; noneffervescent; abrupt boundary

720–740 3C5b3 N4/0; silt; massive; sticky; thin bedded gray silt; slightly effervescent. End.

SITE NAME: GP13

POSITION IN LANDSCAPE: flat lying near channelized drainage along valley wall PARENT MATERIALS: graded fill over silty alluvium/colluvium, basal Superior red clay, and Agassiz gray silt…