Hydrology of the Black Hills Area, South Dakota

Home , Black Hills, Deadwood Formation, Spearfish Formation

By Daniel G. Driscoll, Janet M. Carter, Joyce E. Williamson, and Larry D. Putnam

ABSTRACT systems within the Madison and Minnelusa aquifers also is presented. The Black Hills Hydrology Study was initiated in 1990 to assess the quantity, quality, and distribution of surface water and ground water in INTRODUCTION the Black Hills area of South Dakota. This report summarizes the hydrology of the Black Hills area The Black Hills area is an important resource and the results of this long-term study. center that provides an economic base for western The Black Hills area of South Dakota and South Dakota through tourism, agriculture, the timber Wyoming is an important recharge area for several industry, and mineral resources. In addition, water orig- regional, bedrock aquifer systems and various inating from the area is used for municipal, industrial, local aquifers; thus, the study focused on describ- agricultural, and recreational purposes throughout ing the hydrologic significance of selected bed- much of western South Dakota. The Black Hills area rock aquifers. The major aquifers in the Black also is an important recharge area for aquifers in the Hills area are the Deadwood, Madison, Minnelusa, northern Great Plains. Minnekahta, and Inyan Kara aquifers. The highest Population growth, resource development, and priority was placed on the Madison and Minnelusa periodic droughts have the potential to affect the quantity, quality, and availability of water within the Black aquifers, which are used extensively and heavily Hills area. Because of this concern, the Black Hills influence the surface-water resources of the area. Hydrology Study was initiated in 1990 to assess the Within this report, the hydrogeologic frame- quantity, quality, and distribution of surface water and work of the area, including climate, geology, ground water in the Black Hills area of South Dakota ground water, and surface water, is discussed. (Driscoll, 1992). This long-term study has been a coop- Hydrologic processes and characteristics for erative effort between the U.S. Geological Survey ground water and surface water are presented. For (USGS), the South Dakota Department of Environment ground water, water-level trends and comparisons and Natural Resources, and the West Dakota Water and water-quality characteristics are presented. Development District, which represents various local For surface water, streamflow characteristics, and county cooperators. responses to precipitation, annual yields and yield The specific objectives of the Black Hills efficiencies, and water-quality characteristics are Hydrology Study included: presented. Hydrologic budgets are presented for 1. Inventorying and describing precipitation amounts, ground water, surface water, and the combined streamflow rates, ground-water levels of selected ground-water/surface-water system. A summary aquifer units, and selected water-quality charac- of study findings regarding the complex flow teristics for the Black Hills area.

Introduction 1 2. Developing hydrologic budgets to define relations October 1 through September 30. Discussions of time- among precipitation, streamflow, and aquifer frames refer to water years, rather than calendar years, response for selected Black Hills watersheds. unless specifically noted otherwise. 3. Describing the significance of the bedrock aquifers in the Black Hills area hydrologic system, with an emphasis on the Madison and Minnelusa aquifers, Description of Study Area through determination of: a. aquifer properties (depth, thickness, structure, The study area for the Black Hills Hydrology storage coefficient, hydraulic conductivity, Study consists of the topographically defined Black etc.); Hills and adjacent areas located in western South b. the hydraulic connection between the aquifers; Dakota (fig. 1). Outcrops of the Madison Limestone c. the source aquifer(s) of springs; and Minnelusa Formation, as well as the generalized d. recharge and discharge rates, and gross volu- outer extent of the Inyan Kara Group, which approxi- metric budgets; and mates the outer extent of the Black Hills area, also are e. regional flow paths. shown in figure 1. The Black Hills are situated between 4. Developing conceptual models of the hydrogeo- the Cheyenne and Belle Fourche Rivers. The Belle logic system for the Black Hills area. Fourche River is the largest tributary to the Cheyenne River. The study area includes most of the larger com- munities in western South Dakota and contains about Purpose and Scope one-fifth of the State’s population. The Black Hills uplift formed as an elongated The purpose of this report is to summarize the dome about 60 to 65 million years ago during the Lara- hydrology of the Black Hills area and present major mide orogeny (Darton and Paige, 1925). The dome findings pertinent to the objectives of the Black Hills trends north-northwest and is about 120 mi long and Hydrology Study. The information summarized in this 60 mi wide. Land-surface altitudes range from 7,242 ft report has been presented in more detail in previous above sea level at Harney Peak to about 3,000 ft in the reports prepared as part of the study. Because the Black adjacent plains. Most of the higher altitudes are heavily Hills area of South Dakota and Wyoming is an impor- forested with ponderosa pine, which is the primary tant recharge area for several regional, bedrock aquifers product of an active timber industry. White spruce, and various local aquifers, the study concentrated on quaking aspen, paper birch, and other native trees and describing the hydrogeology and hydrologic signifi- shrubs are found in cooler, wetter areas (Orr, 1959). cance of selected bedrock aquifers. The highest priority The lower altitude areas surrounding the Black Hills was placed on the Madison and Minnelusa aquifers because: (1) these aquifers are heavily used and could primarily are urban, suburban, and agricultural. be developed further; (2) these aquifers are connected Numerous deciduous species such as cottonwood, ash, to surface-water resources through streamflow loss elm, oak, and willow are common along streams in the zones and large springs; and (3) hydraulic connection lower altitudes. Rangeland, hayland, and winter wheat between these aquifers is extremely variable. The farming are the principal agricultural uses for dryland Deadwood and Minnekahta aquifers had a lower pri- areas. Alfalfa, corn, and vegetables are produced in ority because they are used less and have less influence bottom lands and in irrigated areas. Various other on the hydrologic system. The fractured Precambrian crops, primarily for cattle fodder, are produced in both rocks, Inyan Kara Group, and various local aquifers, dryland areas and in bottom lands. including minor bedrock aquifers and unconsolidated Beginning in the 1870’s, the Black Hills have aquifers, had the lowest priorities because: (1) the Pre- been explored and mined for many commodities cambrian and local aquifers are not regional aquifers including gold, silver, tin, tungsten, mica, feldspar, with regional flowpaths; and (2) the Inyan Kara Group bentonite, beryl, lead, zinc, uranium, lithium, sand, is not used as extensively in the Black Hills area as the gravel, and oil (U.S. Department of Interior, 1967). other priority units. Mines within the study area have used various tech- Hydrologic analyses within this report generally niques including placer mining, underground mining, are by water year, which represents the period from and open-pit mining.

2 Hydrology of the Black Hills Area, South Dakota o 104o 45' 103 30' Indian Horse o Belle Fourche 44 45' Reservoir Cr EXPLANATION Owl Newell BELLE Creek OUTCROP OF MADISON LIMESTONE Creek Nisland (from Strobel and others, 1999) F BELLE FOURCHE O UR CHE RIVER OUTCROP OF MINNELUSA FORMATION Hay Creek R (from Strobel and others, 1999) E BUTTE CO Vale R I V TER LAWRENCE CO MEADE CO REDWA APPROXIMATE EXTENT OF THE BLACK Cox Saint Creek HILLS AREA, REPRESENTED BY Lake Crow Onge

Creek GENERALIZED OUTER EXTENT OF reek 30' Gulch Spearfish C INYAN KARA GROUP (modified Whitewood from Strobel and others, 1999) Gulch

Bottom Creek e ls Bear a Creek F Whitewood Butte Higgins Cr Creek Squ STURGIS Spearfish a Central Tinton w Cr City li Iron Cr ka o ood DEADWOOD l Cr w A 15' 103 ad Beaver Cr e D Cr Lead Bear h nnie Cr s A erry i trawb f S r Cr Creek Tilford a e Whitetail p Elk S

Little Creek Roubaix ek Creek N Elk re Elk

Little . C 15' h F Boxelder fis o r r Piedmont a k e Ellsworth R p a S Air Force S. Fork Rapid Cr p i Base d Nemo

C Creek r Blackhawk Cold S pri Cr ng ee s k Box Elder k For Rochford s adN o . For Rapid h k Ca R stle RAPID CITY Castle Cr Beav e Rapid r k Pactola Creek C C ree r C e re Reservoir e e Creek

k k Castle V Deerfield ictoria Creek Reservoir Spring o S. Fork r

44 C l e Cast Rockerville Sheridan Creek Creek Lake Hill City Mt. Rushmore National Keystone Memorial yon an Spring Harney Hayward LIMESTONE PLATEAU C n Peak o x y

n PENNINGTON CO

n Battle o a y Spok Hermosa C n CUSTER CO an a e Creek Creek s C le o Grace Bear B French Creek CUSTER Gulch Redbird e Gillette idg Creek Cool 45' Jewel Cave CUSTER National Monument Beaver STATE French Fairburn PARK

Canyon Creek gh Hi la Lame Canyon n Creek d Pringle Wind Cave

National CreekPark WYOMING

Wind Johnny

Cave SOUTH DAKOTA SOUTH Dewey Beaver Red Creek Buffalo Gap RIVER 30' Hell Creek

FALL RIVER CO H on ot roo ny B k Ca HOT SPRINGS Minnekahta Fall Oral R

CHEYENNE Cascade Springs SOUTH DAKOTA Black Edgemont Horsehead Hills Mi Angostura ss ou o Creek Reservoir Creek r 43 15' d i oo w Area n o tt River o Igloo Creek shown C Provo

Hat

Base modified from U.S. Geological Survey digital data, 01020MILES 1:100,000, 1977, 1979, 1981, 1983, 1985 Rapid City, Office of City Engineer map, 1:18,000, 1996 Universal Transverse Mercator projection, zone 13 01020KILOMETERS

Figure 1. Area of investigation for the Black Hills Hydrology Study.

Introduction 3 Acknowledgments HYDROGEOLOGIC FRAMEWORK

The authors acknowledge the efforts of the West The Black Hills are located within the Great Dakota Water Development District for helping to Plains physiographic province in western South Dakota develop and support the Black Hills Hydrology Study. and eastern Wyoming (fig. 2). The Black Hills strongly West Dakota’s coordination of various local and county influence the hydrology of western South Dakota and cooperators has been a key element in making this northeastern Wyoming. Many streams in western study possible. The authors also recognize the South Dakota originate in the Black Hills, and major numerous local and county cooperators represented by bedrock aquifers are recharged along outcrop areas in West Dakota, as well as the numerous private citizens the Black Hills. Ground and surface water interact who have helped provide guidance and support for the extensively in the Black Hills, and both streamflow and Black Hills Hydrology Study. The South Dakota aquifer recharge are influenced by climatic conditions. Department of Environment and Natural Resources has Overviews of the climate, geology, ground water, and provided support and extensive technical assistance to surface water are provided in the following sections. the study. In addition, the authors acknowledge the input and technical assistance from many faculty and students at the South Dakota School of Mines and Technology.

o o o 112 o CANCANADAADA o 100o 98 49 110 108o 106o 104o 102 Souris Red

S W BO UNITED STSTATESATES E W E D D T O O River G M IN River R E POPLAR A o S BEARPAW DOME S 48 of UPLIFT HINSDALE FAULTPOPLAR FAULT PROVINCE A NESSON PROVINCE R ANTICLINE the C Missouri Little Rocky H Mts River River Judith Mts TH DAKOTA North BLO EEK NORTHNORMissouri DAKOTA Big OD CR SYNCLINE CEDAR CREEK Little Snowy WELDON BROCKTON FAULT MONTMONTANAANA Belt Mts CAT CREEK FAULT ANTICLINE HELENA Mts WHEATLAND SUMATRA BISMARCK SYNCLINE PORCUPINE Missouri WILLOW CREEK SYNCLINE DOME WILLISTON BASIN o FAULT PHYSIOGRAPHIC 46 CRAZY RiverMILES BULL PHYSIOGRAPHIC MOUNTMOUNTAINSAINS CITY MOUNTAIN River LAKE BASIN FAULT BASIN Yellowstone BASIN Approximate

ARCH boundary of BearBeartooth Mts River tooth Mts Williston Pryor Little POPOWDERWDER PLAINS Basin Mts LOWLANDS NYE-BOWLER RIVER BASIN AKOTA FAULT River SOUTH DDAKOTA Bighorn Mts River OVERTHRUST Absaroka Mts PIERRE

GREAT 44o Fourche River CENTRAL BLACK Area of Owl Creek Mts Powder Belle HILLS Sioux Uplift BELT UPLIFT Cheyenne

CASPER IDIDAHO White AHO ARCH Wind River Mts WYWYOMINGOMING FAULT CHADRON ARCH CASPER MTN SWEETWATER North Laramie Mts UPLIFT o GREEN 42 RIVER HARTVILLEUPLIFT BASIN RED HANNA Platte DESERT BASIN LARAMIE NEBRASKA Medicine ROCK BASIN BASIN River UTUTAHAH Bow Mts ALLIANCE BASIN River SPRINGS UPLIFT Sierra CHEYENNE Platte SALT LAKE Madre River LINCOLN CITY Uinta Mts WASHAKIE Mts BASIN COLORADO Platte S.

0 100 200 MILES

0 100 200 KILOMETERS

Figure 2. Present-day structural and physiographic features in the northern Great Plains area (modified from Peterson, 1981, and Busby and others, 1995).

4 Hydrology of the Black Hills Area, South Dakota Climatic Framework Local conditions also are affected by regional climatic patterns, with the northern Black Hills influ- The overall climate of the Black Hills area is enced primarily by moist air currents from the north- continental, with generally low precipitation amounts, west, and the southern Black Hills influenced primarily hot summers, cold winters, and extreme variations in by drier air currents from the south-southeast. As a both precipitation and temperatures (Johnson, 1933). result, annual precipitation averages about 16 to Local climatic conditions are affected by topography, 17 inches for most of Fall River County (fig. 4) and is with generally lower temperatures and higher precipi- much less than parts of Lawrence and Meade Counties tation at the higher altitudes. The average annual tem- perature is 43.9°F (U.S. Department of Commerce, that have comparable altitudes. Boxplots showing the 1999) and ranges from 48.7°F at Hot Springs to distribution of annual precipitation for the study area approximately 37°F near Deerfield Reservoir. and for counties within the study area during 1931-98 Precipitation data sets used for this study gener- are presented in figure 5. For the study area, the long- ally were taken from Driscoll, Hamade, and Kenner term average of 18.61 inches is slightly larger than the (2000), who summarized available precipitation data median (50th percentile) of 17.96 inches. The 90th per- (1931-98) for the Black Hills area. These investigators centile indicates that annual precipitation over the compiled monthly precipitation records for 52 long- study area is less than about 23.70 inches 90 percent of term precipitation gages operated by National Oceanic the time. Annual precipitation for both Butte and Fall and Atmospheric Administration (1998) and 42 short- River Counties is less than the long-term average for term precipitation gages operated by the USGS. These the study area about 75 percent of the time. data sets are available on the World Wide Web at The largest precipitation amounts typically occur http://sd.water.usgs.gov/projects/bhhs/precip/ during May and June, and the smallest amounts typi- home.htm. A geographic information system (GIS) cally occur during November through February (fig. 6). was used by Driscoll, Hamade, and Kenner (2000) to The most variable month is May, during which precip- generate spatial distributions of monthly precipitation itation has ranged from a minimum of about 0.4 inch to data for 1,000-by-1,000-meter grid cells for the study area; an example is shown in figure 3. Monthly distri- a maximum of 8.5 inches. The seasonal distribution of butions were composited to produce annual distribu- precipitation is fairly uniform throughout the study tions for counties within the study area and for drainage area; however, Lawrence County receives slightly areas of selected streamflow-gaging stations; these data larger proportions of its annual precipitation during sets were presented by Driscoll and Carter (2001). The winter months than the other counties (fig. 7). precipitation distributions were used extensively for Long-term (1931-98) trends in precipitation various applications including evaluating responses of (fig. 8) are an important consideration for hydrologic ground-water levels and streamflow to precipitation, analysis for the Black Hills area. Figure 8A shows that estimating precipitation recharge for bedrock aquifers, annual precipitation for the study area averages and developing long-term hydrologic budgets. 18.61 inches and has ranged from 10.22 inches in 1936 Spatial precipitation patterns in the Black Hills to 27.39 inches in 1995. Figure 8B shows that the asso- area are highly influenced by orography, as shown by ciated departures (from the average) have ranged from an isohyetal map (fig. 4) for 1950-98, which is the a deficit (-) of 8.39 inches to a surplus (+) of period commonly used for hydrologic budgets pre- 8.78 inches, respectively. The cumulative trends are sented in this report. Areas of relatively low precipita- readily apparent from figure 8C, with the most pro- tion occur in the low altitudes around the periphery of the Black Hills. Most areas with altitudes exceeding nounced trends identified by the longest and steepest 6,000 ft above sea level have average annual precipita- line segments. Sustained periods of generally deficit tion in excess of 19 inches, with the largest amounts precipitation occurred during 1931-40 and 1948-61. occurring in the northern Black Hills near Lead, where Sustained periods of generally surplus precipitation the average annual precipitation (1950-98) exceeds occurred during 1941-47, 1962-68, and 1993-98. The 28 inches. Orographic effects also are apparent in the middle to late 1990’s stand out as the wettest period high-altitude areas near Harney Peak. since 1931.

Climatic Framework 5 o 104o 45' 103 30' Indian Horse o Belle Fourche EXPLANATION 44 45' Reservoir Cr Owl Newell PRECIPITATION, IN INCHES BELLE Creek Creek Less than 2 Nisland F BELLE FOURCHE O UR 2 to 3 CHE RIVER

Hay Creek R

E BUTTE CO Vale 3 to 4 R I V TER LAWRENCE CO MEADE CO REDWA 4 to 5 Cox Saint Creek Lake Crow Onge 5 to 6

Creek reek 30' Gulch Spearfish C Greater than 6 Whitewood Gulch

Little Creek Roubaix ek Creek N Elk re Elk

Little . C 15' h F Boxelder fis o r r Piedmont a k e R Ellsworth p a S Air Force S. Fork Rapid Cr p i d Nemo Base

C Creek r Blackhawk Cold S pri Cr ng ee s k Box Elder k For Rochford s adN o . For Rapid h k Ca R stle RAPID CITY Castle Cr Beav e Rapid r k Creek C C ee Pactola r C r e re Reservoir e e Creek k k Castle V Deerfield ictoria Creek Reservoir Spring o S. Fork r 44 C l e Cast Rockerville Sheridan Creek Creek Lake Hill City Mt. Rushmore National Keystone Memorial yon an Spring Harney Hayward

LIMESTONE PLATEAU C n Peak

o x

y n PENNINGTON CO n Battle

a o Spo Hermosa

y k C a n CUSTER CO ne a Creek Creek s C le o Grace Bear B French Creek CUSTER Gulch Redbird e Gillette idg Creek Cool 45' Jewel Cave CUSTER National

Monument Beaver STATE French Fairburn

PARK

Canyon Creek gh Hi la Lame Canyon n Creek d Pringle Wind Cave National Park

Creek WYOMING

Wind Johnny

Cave SOUTH DAKOTA SOUTH Dewey Beaver Red Creek Buffalo Gap RIVER 30' Hell Creek

FALL RIVER CO H on ot roo y B k Can HOT SPRINGS Minnekahta Fall Oral R

CHEYENNE Cascade Springs

Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w n o tt o Igloo Creek C Provo

Figure 3. Monthly precipitation distribution for October 1995 (from Driscoll, Hamade, and Kenner, 2000).

6 Hydrology of the Black Hills Area, South Dakota o 104o 45' 103 30' 3,000 Horse EXPLANATION Belle Fourche Indian o 17 44 45' Reservoir Cr OUTCROP OF MADISON LIME Owl Newell BELLE 3,000 Creek STONE (from Strobel and Creek15 Nisland others, 1999) F BELLE FOURCHE O 16 UR CHE 17 RIVER OUTCROP OF MINNELUSA Hay 18 Creek 19 R

E BUTTE CO Vale FORMATION (from Strobel V R R I ATE LAWRENCE CO MEADE CO and others, 1999) REDW 22 Cox 21 Saint Creek 18 20 LINE OF EQUAL PRECIPITA- Lake Crow 19 4,000 Onge 3,000 TION--Number is average Creek 23 reek 20 Gulch Spearfish C annual precipitation. Interval 30' 4,000 24 Bear Whitewood x Butte 1 inch Gulch

Bottom 25 Creek e 5,000 ls LAND-SURFACE CONTOUR-- Bear a 5,000 Creek F 26 Whitewood Butte Number is altitude above Higgins Cr Creek Squ STURGIS Spearfish a Central Tinton w mean sea level. Contour Cr City li Iron Cr ka o ood DEADWOOD l Cr w A 15' 103 interval 1,000 feet ad Beaver Cr 5,000 e D Cr Lead Bear h nnie Cr s A 7,000 erry i 28trawb f S r Cr Creek Tilford 3,000 a e Whitetail p Cheyenne 27 Elk S Crossing 6,000 Little Creek Roubaix ek Creek N Elk re Elk

Little . C 20 15' h 25 F Boxelder fis o r r Piedmont a k e 24 R Ellsworth p a 3,000 S Air Force S. Fork Rapid Cr p i 19 d Nemo Base

C Creek r Blackhawk Cold S pri Cr ng ee s k Box Elder k For Rochford s 7,000 adN 3,000 23 o . For Rapid h k Ca R stle 5,000 RAPID CITY Castle Cr Beav 7,000 e 4,000 Rapid r k Creek C C ee Pactola r C 22 r e re Reservoir e e Creek k k Castle V 3,000 Deerfield ictoria Creek Reservoir Spring o S. Fork r 44 C 20 l e 21 Cast Rockerville Sheridan Creek Creek Lake Hill City 5,000 Mt. Rushmore 6,000 National Keystone 7,000 Memorial yon an Spring Harney Hayward 18 LIMESTONE PLATEAU Iron C Peak n Mountain

o x7,000 17 y x n PENNINGTON CO n Battle

a o Spo Hermosa

y k C a n CUSTER CO ne a 19 6,000 Creek Creek s C le o Calamity Grace Bear B 6,000 French Peak 20 Creek CUSTER x Gulch Redbird e Gillette lidg 6,000 Creek Coo 45' Jewel Cave CUSTER National

Monument Beaver STATE French Fairburn

PARK

Canyon Creek 5,000 ighl H an Lame Canyon d Creek 3,000 Pringle Wind Cave National Park Creek WYOMING 5,000 Wind Johnny

Cave SOUTH DAKOTA SOUTH Dewey 18 Onyx Beaver Red Cave Creek 17 Buffalo Gap RIVER 30' Hell 4,000 Creek

FALL RIVER CO H on ot Broo y k Can HOT SPRINGS 3,000 Minnekahta Fall 16 Oral R

CHEYENNE 4,000 4,000 Cascade Springs 4,000

Edgemont Horsehead Angostura o Creek Reservoir Creek 43 15' d oo w n o tt o Igloo Creek C Provo

Hat 01020MILES Base modified from U.S. Geological Survey digital data, 1:100,000, 1977, 1979, 1981, 1983, 1985 Rapid City, Office of City Engineer map, 1:18,000, 1996 01020KILOMETERS Universal Transverse Mercator projection, zone 13 Figure 4. Isohyetal map showing distribution of average annual precipitation for Black Hills area, water years 1950-98 (from Carter, Driscoll, and Hamade, 2001).

Climatic Framework 7 40 EXPLANATION Maximum 90th percentile 30 75th percentile Median 25th percentile 10th percentile 20 Minimum

Long-term average for study area 10 (18.61 inches) ANNUAL PRECIPITATION, IN INCHES

Butte Meade Custer Lawrence Fall River Study area Pennington

Figure 5. Distribution of annual precipitation for the study area and counties within the study area, water years 1931-98 (modified from Driscoll and Carter, 2001).

100 50

20 10 EXPLANATION 5 Maximum 90th percentile 2 75th percentile 1 Median 0.5 25th percentile 10th percentile 0.2 Minimum 0.1 PRECIPITATION, IN INCHES PRECIPITATION, 0.05

0.02 0.01 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

Figure 6. Distribution of monthly precipitation for the study area, water years 1931-98 (from Driscoll, Hamade, and Kenner, 2000).

8 Hydrology of the Black Hills Area, South Dakota 10

Study area 5 Lawrence County Fall River County

0.5

0.2

0.1

MEAN MONTHLY PRECIPITATION, IN INCHES PRECIPITATION, MEAN MONTHLY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP

Figure 7. Mean monthly precipitation for study area and selected counties, water years 1931-98 (from Driscoll and Carter, 2001).

A Annual precipitation for the entire study area 30

10 IN INCHES Annual precipitation Long-term average (18.61 inches)

ANNUAL PRECIPITATION, ANNUAL 0 B Annual departure from long-term average 10

IN INCHES -5 ANNUAL DEPARTURE, ANNUAL -10 C Cumulative departure from long-term average 0

-10

-20

-30 IN INCHES -40

-50 CUMULATIVE DEPARTURE, CUMULATIVE 1930 1940 1950 1960 1970 1980 1990 2000 YEAR

Figure 8. Long-term trends in precipitation for the Black Hills area, water years 1931-98 (from Driscoll, Hamade, and Kenner, 2000).

Climatic Framework 9 The long-term precipitation trends are especially in the Precambrian basement and modified during the important because of potential for bias in analysis and Laramide orogeny (Downey, 1984). interpretation of available hydrologic data sets, which During Paleozoic time, the area generally was are much more abundant for the recent wet years. broad, flat, and covered by shallow, warm seas Water-level records are available for 71 observation (Downey, 1984). Numerous disconformities during wells in the Black Hills area for 1998, compared with Paleozoic time indicate intermittent transgressions and five wells for 1965 (Driscoll, Bradford, and Moran, regressions when seas advanced from west to east in 2000). Miller and Driscoll (1998) reported streamflow response to tectonic activity of the Antler orogeny to records for 65 gages for 1993, compared with 30 gages the west (Sandberg and Poole, 1977). Deposits gener- for 1960. Thus, the potential for bias is an important ally were beach, shallow marine, carbonate, sabkha, consideration in analysis of hydrologic data sets for the and evaporite units (Redden and Lisenbee, 1996). Black Hills area. During Cretaceous time, the area was covered by Average annual potential evaporation generally a north-south trending sea, which extended from the exceeds average annual precipitation throughout the Gulf of Mexico to the Arctic Ocean (Downey, 1986). study area. Thus, evapotranspiration generally is During Late Cretaceous time, the sea was at its widest limited by precipitation amounts and availability of soil extent, but marine deposition was interrupted by fre- moisture. Average pan evaporation for April through quent east-west regressions (Anna, 1986). October is about 30 inches at Pactola Reservoir and about 50 inches at Oral (U.S. Department of Paleostructure Commerce, 1999). The Northern Great Plains area was part of the Cordilleran platform throughout most of Paleozoic Geologic Framework time. The Williston Basin, which covers parts of North Dakota, South Dakota, southern Saskatchewan, south- The stratigraphic and structural features in the western Manitoba, and eastern Montana (fig. 10), Black Hills area are complex. Many of the geologic began to take shape during Ordovician time (Carlson formations, such as the Deadwood Formation, Madison and Anderson, 1965). Other major Jurassic and Creta- Limestone, Minnelusa Formation, Minnekahta Lime- ceous (pre-Laramide) paleostructural elements stone, and Inyan Kara Group, in the Black Hills (fig. 9) (fig. 10) include the Powder River Basin, the Central are regionally extensive. Several formations thin or Montana trough and uplift, the Cedar Creek anticline, pinch out in southern and eastern South Dakota. To and the Alberta shelf (Anna, 1986). better understand the stratigraphic and structural set- The Laramide orogeny, which affected the tings in the Black Hills, an overview of the regional eastern Rocky Mountains of the United States, began geologic setting is provided first and is followed by an during late Cretaceous time and continued in the overview of the local geologic setting. Eocene period (Redden and Lisenbee, 1996). The Laramide orogeny was characterized by large-scale warping, deep erosion of uplifts, and deposition of oro- Regional Geologic Setting genic sediments into basins (Tweto, 1975). Most, if not Parts of Montana, North Dakota, South Dakota, all, pre-Laramide structural features (fig. 10) were and Wyoming are included in the Northern Great Plains reactivated and became more prominent during the area. The present-day structural features (fig. 2) of the Laramide orogeny (Anna, 1986). During the Laramide Northern Great Plains are directly related to the geo- orogeny, the Bighorn and Laramie Mountains, the logic history of the Cordilleran platform, which is a Black Hills, and the Central Montana uplift formed, part of the stable interior of the North American Conti- and the Williston and Powder River Basins (fig. 2) nent (Downey, 1986). The present-day structure prob- were downwarped into essentially their present config- ably was controlled by the pre-existing structural grain uration (Anna, 1986).

10 Hydrology of the Black Hills Area, South Dakota Principal horizon of limestone lenses giving teepee buttes. Dark-gray shale containing scattered concretions. Widely scattered limestone masses, giving small teepee buttes. Black fissile shale with concretions. Light colored clays with sandstone channel fillings and local limestone lenses. Impure slabby limestone. Weathers buff. Dark-gray calcareous shale, with thin Orman Lake limestone at base. Gray shale with scattered limestone concretions. Clay spur bentonite at base. Light-gray siliceous shale. Fish scales and thin layers of bentonite. Brown to light-yellow and white sandstone. Massive to thin-bedded, brown reddish-brown sandstone. Yellow, brown, and reddish brown massive to thinly bedded sandstone, pebble conglomerate, siltstone, and claystone. Local fine-grained limestone coal. Red silty shale, soft red sandstone and siltstone with gypsum thin limestone layers. Gypsum locally near the base. Thin to medium-bedded, fine-grained, purplish gray laminated limestone. Red shale and sandstone. Yellow to red cross-bedded sandstone, limestone, and anhydrite locally at top. Red shale with interbedded limestone and sandstone at base. Massive light-colored limestone. Dolomite in part. Cavernous upper Pink to buff limestone. Shale locally at base. Buff dolomite and limestone. Green shale with siltstone. Massive to thin-bedded buff purple sandstone. Greenish glauconitic shale flaggy dolomite and flat-pebble limestone conglomerate. Sandstone, with conglomerate locally at the base. Schist, slate, quartzite, and arkosic grit. Intruded by diorite, metamorphosed to amphibolite, and by granite pegmatite. Light-gray shale with numerous large concretions and sandy layers. Dark-gray shale Includes rhyolite, latite, trachyte, and phonolite. Green to maroon shale. Thin sandstone. Massive fine-grained sandstone. Greenish-gray shale, thin limestone lenses. Glauconitic sandstone; red sandstone near middle. Red siltstone, gypsum, and limestone. Interbedded sandstone, limestone, dolomite, shale, and anhydrite. -- 0-25 0-45 25-65 0-235 0-150 0-500 0-150 30-60 0-300 0-220 0-225 80-300 Impure chalk and calcareous shale. 25-150 1 1 1 1 10-200 10-190 25-485 350-750 1 1 225-380 150-850 125-230 150-270 Dark-gray to black siliceous shale. 250-450 375-800 375-1,175 1 <200-1,000 1 1,200-2,700 IN FEET 1 THICKNESS South Dakota School of Mines and Technology (written commun., January 1994) NEWCASTLE SANDSTONE Fuson Shale Minnewaste Limestone Chilson Member Goose Egg Equivalent Turner Sandy Member Wall Creek Member Redwater Member Lak Member Hulett Member Stockade Beaver Mem. Canyon Spr Member Modified from information furnished by the Department of Geology and Geological Engineering, MOWRY SHALE

MUDDY

STRATIGRAPHIC UNIT DESCRIPTION FM

SANDSTONE LAKOTA

BELLE FOURCHE SHALE SKULL CREEK SHALE FALL RIVER FORMATION

PIERRE SHALE NIOBRARA FORMATION GROUP UNDIFFERENTIATED ALLUVIUM AND COLLUVIUMWHITE RIVER GROUP 0-50 Sand, gravel, boulder, and clay. GREENHORN FORMATION SUNDANCE FORMATION GYPSUM SPRING FORMATION MINNEKAHTA LIMESTONE OPECHE SHALE MINNELUSA FORMATION MADISON (PAHASAPA) LIMESTONE ENGLEWOOD FORMATION WHITEWOOD (RED RIVER) FORMATION WINNIPEG FORMATION DEADWOOD FORMATION UNDIFFERENTIATED IGNEOUS AND METAMORPHIC ROCKS SPEARFISH FORMATION INTRUSIVE IGNEOUS ROCKS MORRISON FORMATION CARLILE SHALE UNKPAPA SS

GRANEROS GROUP GRANEROS INYAN KARA INYAN Ju Po Tw Ou Kik Tui R Kps pCu Pmk OCd T Ps P Pm QTac MDme FOR INTERVAL ABBREVIATION STRATIGRAPHIC PERMIAN TRIASSIC SYSTEM TERTIARY JURASSIC DEVONIAN CAMBRIAN ORDOVICIAN QUATERNARY CRETACEOUS MISSISSIPPIAN & TERTIARY (?) Stratigraphicfor the Black Hills.section PENNSYLVANIAN

. AEZI EOOCCENOZOIC MESOZOIC PALEOZOIC PRECAMBRIAN ERATHEM Modified based on drill-hole data 1 Figure 9

Geologic Framework 11 Base from U.S. National Atlas 0 100200 300 400 MILES 1:17,000,000, 1970 0 100200 300 400 KILOMETERS

Figure 10. Regional paleostructure during Jurassic and Cretaceous time in the western interior of the United States (modified from Anna, 1986).

12 Hydrology of the Black Hills Area, South Dakota Stratigraphy thin to zero thickness near the axis of the central Precambrian rocks form the basement in the Montana trough (Downey, 1986; figs. 10 and 11). northern Great Plains area. Precambrian rocks are A sequence of red shale, siltstone, and evaporite exposed in the central core of many of the mountain deposits belonging to the upper part of the Goose Egg ranges, but lie greater than 15,000 ft below land surface and Spearfish Formations of Triassic age overlie the at the center of the Williston Basin (Downey and Minnelusa Formation (Downey and Dinwiddie, 1988). Dinwiddie, 1988). Jurassic rocks, which include the Nesson, Piper, Rocks of Cambrian and Ordovician age consist Rierdon, and Sundance Formations and their equiva- of sandstone, shale, limestone, and dolomite and repre- lents (fig. 12) are predominantly carbonate, shale, and sent the shoreward facies of a transgressive sea calcareous shale (Anna, 1986). (Peterson, 1981). The extent of the Cambrian and Deposits during Cretaceous time primarily were Ordovician rocks in the northern Great Plains area is sandstones, shales, and minor carbonates (Redden and shown in figure 11. The principal geologic units of Lisenbee, 1996). A number of formation names have Cambrian and Ordovician age are the Deadwood been applied to the various Cretaceous units in the Formation, Emerson Formation, Winnipeg Formation, northern Great Plains area; however, in several Red River Formation (Whitewood Formation), and instances, these formation names are used only in one Stony Mountain Formation (fig. 12). Rocks of Cam- State or subregion (fig. 13). Lower Cretaceous rocks brian and Ordovician age extend into Canada where (fig. 13) range in thickness from zero in eastern North they are exposed along the Precambrian shield Dakota and South Dakota to more than 1,400 ft in west- (Downey, 1986). Erosion during Devonian time trun- central Wyoming (Anna, 1986). The extent of the cated the Ordovician geologic units in South Dakota Lower Cretaceous sandstones, which include the Inyan and Wyoming to the south of a line extending between Kara Group, Muddy Sandstone, and Newcastle or the central Black Hills and southern Bighorn Moun- Dakota Sandstone, is shown in figure 11. The sedimen- tains (Peterson, 1981). Rocks of Silurian age are not tary pattern of Upper Cretaceous rocks (fig. 13) is asso- present in the Black Hills area. ciated with four main transgressions and regressions of The extent of Mississippian rocks in the northern shallow seas. Great Plains area is shown in figure 11. These rocks Tertiary units (fig. 13) generally were deposited overlying the Bakken Formation (where present) are in a continental environment (Downey, 1986). Deposits termed the Madison Limestone, or Madison Group of Quaternary age in the northern Great Plains area where divided (fig. 12). The Madison Limestone con- consist of alluvium, glacial materials, and other surfi- sists of a sequence of marine carbonates and evaporites cial deposits. Alluvial deposits fill major drainages in deposited mainly in a warm, shallow-water environ- the area. Glacial deposits are located only in the eastern ment (Downey, 1986). Development of karst (solution) parts of North Dakota and South Dakota and in the features in the Madison Limestone was common northernmost part of Montana (Downey, 1986). because the carbonate rocks are relatively soluble in water (Downey, 1986). Complex and interconnected Local Geologic Setting solution features developed in the Madison Limestone during tropical conditions when it was exposed at or The Black Hills uplift is a northwest-trending, near land surface (Busby and others, 1995). Large and asymmetric, elongate dome, or doubly plunging anti- extensive cave systems have formed in the outcrop cline. Uplift began about 62 million years ago during areas of the Madison Limestone in the Bighorn the Laramide orogeny and probably continued in the Mountains and in the Black Hills. Eocene period (Redden and Lisenbee, 1996). Large Rocks of Pennsylvanian age consist primarily of anticlines occur on the northern and southern flanks of marine sandstone, shale, siltstone, and carbonate. The the Black Hills and plunge away from the uplift into the Pennsylvanian rocks are divided into many different surrounding plains. Numerous smaller folds, faults, geologic units (fig. 12). Rocks of Pennsylvanian-age domes, and monoclines also occur in the Black Hills have been truncated by pre-Jurassic erosion progres- (fig. 14). Igneous intrusions were emplaced on the sively northward across central Montana; these rocks northern flanks of the uplift during the Tertiary Period.

Geologic Framework 13 ● ●

● ●

Falls Falls

Sioux Sioux

● ●

Fargo

Grand Forks Grand

o o 1988; Whitehead, 1996 1988; Whitehead, 1996

★ ★

100

Pierre Pierre

★ ★

Bismarck Bismarck Modified from Downey and Dinwiddie,

Modified from Downey and Dinwiddie,

S O U T H D A K O T A T O K A D H T U O S

N O R T H D A K O T A T O K A D H T R O N

Rapid City Rapid Rapid City Rapid

● ●

o o

★ ★

105 105

Cheyenne

Casper

Casper ● ● Cretaceous-age rocks

Billings Billings ● ● Mississippian-age rocks

o o

W Y O M I N G W Y O M I N G

110 110 ● ●

M O N T A N A M O N T A N A

Great Falls Great Falls Base modified from U.S. Geological Survey digital data, 1:2,000,000, 1972 Base modified from U.S. Geological Survey digital data, 1:2,000,000, 1972

o o

43 43 ★ ★

Butte Butte ● ● MILES

Helena Helena MILES 100 100 ogic periods. 100 KILOMETERS o o 100 KILOMETERS 50 50

115 115 50 50 0 0 0 0

o o

48 48 for selected geol ● ●

● ●

Falls

Sioux

Falls Sioux

● ●

Fargo

Grand Forks Grand

o o 1988; Whitehead, 1996

★ ★

100

Pierre Pierre

★ ★

Bismarck Bismarck

Modified from Downey and Dinwiddie,

S O U T H D A K O T A T O K A D H T U O S

N O R T H D A K O T A T O K A D H T R O N

Rapid City Rapid Rapid City Rapid Modified from Downey and Dinwiddie, 1988 ● ●

the northern Great Plains area the

o o

★ ★

105 105

Cheyenne

Casper

Casper ● ● Pennsylvanian-age rocks

Billings Billings ● ●

o o

W Y O M I N G W Y O M I N G

110 110 Cambrian and Ordovician-age rocks ● ●

M O N T A N A M O N T A N A

Great Falls Great Falls Base modified from U.S. Geological Survey digital data, 1:2,000,000, 1972 Base modified from U.S. Geological Survey digital data, 1:2,000,000, 1972

o o

43 43 ★ ★

Butte Butte ● ● MILES

Helena Helena MILES Approximate extent of rocks in of rocks extent Approximate 100 100

. 100 KILOMETERS o o 100 KILOMETERS 50 50

115 115 50 50 0 0 0 0

o o

48 48 Figure 11

14 Hydrology of the Black Hills Area, South Dakota South-Central Western Central North-Central Series Powder River Basin Williston Basin Montana South Dakota Montana Trough Montana SYSTEM

JURASSIC MIDDLE JURASSIC Piper Formation Piper Formation Gypsum Spring Formation Piper Formation Piper Formation Piper Formation

TRIASSIC Chugwater Formation Chugwater Formation

Spearfish Formation Spearfish Formation UPPER PERMIAN Goose Egg Formation

Minnekahta Limestone Minnekahta Limestone PERMIAN Opeche Shale Opeche Shale LOWER PERMIAN

UPPER PENNSYLVANIAN

Tensleep Minnelusa Formation Sandstone Minnelusa Tensleep Sandstone MIDDLE Formation Tensleep Sandstone Minnelusa Formation PENNSYLVANIAN Amsden Group Amsden Group (upper part) (upper part) Amsden PENNSYLVANIAN LOWER Formation Amsden Formation PENNSYLVANIAN Tyler Formation Tyler Formation of Amsden Group

Big Snowy Heath Formation Big Snowy Heath Formation Group Otter Formation Group Otter Formation UPPER Kibbey Formation Kibbey Formation MISSISSIPPIAN

Charles Charles Charles Formation Formation Formation

Madison Limestone Mission Canyon Mission Canyon Mission Canyon Mission Canyon or Madison Group Madison Group Limestone MISSISSIPPIAN Madison Limestone Madison Group Limestone Limestone Limestone Pahasapa Limestone LOWER Madison Group MISSISSIPPIAN Lodgepole Lodgepole Lodgepole Lodgepole Limestone Limestone Limestone Limestone

Englewood Formation Bakken FormationBakken Formation Bakken Formation

Three Forks Formation Three Forks Formation UPPER Three Forks Formation Three Forks Formation Three Forks Formation DEVONIAN Birdbear Formation Birdbear Formation Jefferson Formation Jefferson Formation Jefferson Formation Duperow Formation Duperow Formation Souris River Formation Souris River Formation Dawson Bay Formation MIDDLE

DEVONIAN DEVONIAN Prairie Formation Winnipegosis Formation

LOWER DEVONIAN

UPPER SILURIAN

MIDDLE SILURIAN SILURIAN Interlake Formation

LOWER SILURIAN Interlake Formation

Stony Mountain Stony Mountain Formation Formation UPPER Red River Formation ORDOVICIAN Bighorn Bighorn Dolomite or Red River Formation Red River Formation Red River Formation Red River Formation Dolomite Whitewood Dolomite

MIDDLE Winnipeg Formation Winnipeg Formation Winnipeg Formation Winnipeg Formation Winnipeg Formation ORDOVICIAN ORDOVICIAN

LOWER ORDOVICIAN

Snowy Range Snowy Range Deadwood Formation Formation or Formation or UPPER Deadwood Deadwood Gallatin and Gallatin and Deadwood Formation Emerson Formation Emerson Formation CAMBRIAN Gros Ventre Formation Gros Ventre Formation Formations Formations or equivalents or equivalents

MIDDLE Flathead Flathead

CAMBRIAN CAMBRIAN Sandstone Sandstone Flathead Sandstone Flathead Sandstone

LOWER CAMBRIAN

PRECAMBRIAN

Figure 12. Generalized correlation chart for Paleozoic-age rocks in Montana, North Dakota, South Dakota, and Wyoming (modified from Downey, 1986).

Geologic Framework 15 Eastern Eastern Montana Series and Western Powder North Dakota Western Central Black Hills-- -- System European River Basin-- -- Montana Montana South Dakota Western Eastern Stage Wyoming North Dakota South Dakota

PLIOCENE

Ogallala Fm.

MIOCENE Arikaree Fm.

White River Fm. Western North Dakota White River Only OLIGOCENE White River Fm. Fm. TERTIARY Volcanic rocks Volcanic rocks Volcanic

EOCENE Golden Valley Wasatch Fm. Fm. Western North Dakota Only

Sentinel Butte Mbr. Tongue River Mbr. Tongue River Mbr. Tongue River Mbr. Tongue River Mbr.

PALEOCENE Lebo Shale Mbr. Lebo Shale Mbr. Cannonball Mbr. Lebo ShaleCannonball Mbr. Willow Creek Mbr. Fm. Tullock Mbr. Tullock Mbr. Ludlow Mbr. Ludlow Mbr. Fort Union Fm. Fort Union Fm. Fort Union Fm. Fort Union Fm.

Hell Creek Fm. Lance Fm. Hell Creek Fm. Hell Creek Fm. MAESTRICHTIAN St. Mary River Fm. Fox Hills Ss. Fox Hills Ss. Fox Hills Ss. Fox Hills Ss. ? Horsethief Ss. Lewis Shale Bearpaw Sh. Bearpaw Shale Teapot Ss. Mbr. Pierre Shale Unnamed Pierre Shale Pierre Shale Fm. Mesa CAMPANIAN Verde Parkman Ss. Mbr. Judith River Fm. Two Medicine Fm. Unnamed Claggett Sh. Sussex Ss. Mbr. Virgelle Ss. Eagle Ss. Shannon Ss. Mbr. Mitten Black Sh. Mbr. Pembina Mbr. Sharon Springs Mbr. Steele Sh.

Telegraph Creek Fm. Telegraph Creek Fm. or Cody Sh. Fishtooth ss.* SANTONIAN Niobrara Fm. Niobrara Fm. Niobrara Fm. Niobrara Fm. CONIACIAN Niobrara Mbr. UPPER CRETACEOUS Marias River Shale Carlile Carlile Sh. Carlile Sh. *Bowdoin ss. Cody Sh. Carlile Sh. Sh. TURONIAN Carlile equivalent Greenhorn Fm. Greenhorn Fm. Greenhorn Fm. Greenhorn Fm. Mosby Ss. Mbr. Frontier Fm. CENOMANIAN Belle Fourche Sh. Belle Fourche Sh. Belle Fourche Sh. Belle Fourche Sh.

Bootlegger Mbr. Mowry Sh. Mowry Sh. Mowry Sh. Mowry Sh. Mowry Sh. Vaughn *Bow Dakota Muddy Ss. Muddy Ss. Newcastle Ss. Muddy Ss. Newcastle Ss. Ss./Fm. Mbr. Island ss. (part) Skull Creek Sh. Skull Creek or Skull Creek Sh. Skull Creek Sh. Skull Creek Sh. Taft Hill Mbr. ALBIAN *Basal siltThermopolis Sh. *Basal silt *Basal silt *Basal silt

Blackleaf Fm. Blackleaf Flood Mbr. *First Cat Creek ss. Fall River equivalent Fall River Ss. Fall River Ss. Fall River Ss. CRETACEOUS

Fuson equivalent Fuson Mbr. Fuson Mbr. Fuson Mbr. Sunburst Mbr. *Second Cat Creek ss. Fm. Inyan Kara Gp. Kara Inyan

Kootenai *Third Cat Creek ss. Lakota equivalent Lakota Mbr. Lakota Mbr. Lakota Mbr. APTIAN Cutbank Ss.

Kootenai Fm. Kootenai Mbr. LOWER CRETACEOUS LOWER

NECOMIAN

TITHONIAN ?? ? ? ? KIMMERIDGIAN Morrison Fm. Morrison Fm. Morrison Fm. Morrison Fm. Morrison Fm.

Swift Fm. OXFORDIAN Swift Fm. Swift Fm. Upper part Upper part UPPER JURASSIC Swift Fm.

CALLOVIAN

JURASSIC Lower part Rierdon Fm. Sundance Fm. Sundance Fm. Rierdon Fm. Lower part Rierdon Fm. BATHONIAN Rierdon Fm.

MIDDLE JURASSIC Sawtooth Fm. Piper Fm. Piper Fm. Piper Fm. BAJOCIAN Gypsum Spring Fm. Gypsum Spring Fm. Nesson Fm. Nesson Fm. * Of informal or subsurface usage

Figure 13. Generalized correlation chart for Mesozoic- and Cenozoic-age rocks in Montana, North Dakota, South Dakota, and Wyoming (modified from Downey, 1986).

16 Hydrology of the Black Hills Area, South Dakota o 103o30' 104 45' EXPLANATION Indian Horse Hydrogeologic Stratigraphic o Belle Fourche Creek 44 45' Reservoir Units Units Map Units Owl Newell Creek Unconsolidated QTac Alluvium and colluvium, BELLE units undifferentiated Nisland Creek F BELLE FOURCHE O White River aquifer Tw White River Group UR CHE RIVER Hay Creek Tertiary intrusive Tui Undifferentiated intrusive BUTTE CO Vale units er igneous rocks Riv MEADE CO Redwater LAWRENCE CO Cretaceous- Kps Pierre Shale to Skull Creek Shale, Creek sequence Cox Saint confining unit undifferentiated Crow Lake Onge

Bear Creek d Inyan Kara aquifer Kik Inyan Kara Group o o w 30' Spearfish e Creek t i Jurassic-sequence h Ju Morrison Formation to Sundance Whitewood W semiconfining unit Creek Formation, undifferentiated Spearfish confining Gulch Creek TRPs Spearfish Formation Bottom unit Creek Butte Squ STURGIS Creek a Central Tinton w Minnekahta aquifer Pmk Minnekahta Limestone City o False DEADWOOD Cr Alkali 15' 103 Beaver Cr Opeche confining Lead Po Opeche Shale nnie Cr unit A Crx Bear h s Terry i Tilford f Peak Elk Antelope r a r Minnelusa aquifer PPm Minnelusa Formation e

p Whitetail C S adow RoubaixMe Little Elk reek Creek Madison aquifer MDme Madison (Pahasapa) Limestone 15' N C Creek Spearfish . Boxelder F

Little and Englewood Formation o Piedmont r k Ellsworth R Air Force Ordovician-sequence S. Fork Rapid Cr a Ou Whitewood Formation and p Nemo Base semiconfining unit i Crooks d Winnipeg Formation Tower C Blackhawk Cold S r Creek pri x Deadwood aquifer ng OCd Deadwood Formation Cre s ek k Box Elder For Rochford s ad Precambrian igneous o pCu h Rapid and Undifferentiated igneous R Creek A' metamorphic units Bea and metamorphic rocks ve Castle Creek r Pactola Rapid C r Reservoir e e

k Creek Vi A' Deerfield ctoria Creek A LINE OF GEOLOGIC SECTION 44o S. Fork r Reservoir Spring C e FAULT--Dashed where approximated. A stl Ca Sheridan Rockerville Bar and ball on downthrown side Creek Lake Hill City Creek ANTICLINE--Showing trace of axial Spring Mt. Rushmore Keystone plane and direction of plunge. National o any n Memorial Hayward Dashed where approximated LIMESTONE PLATEAU C n Harney o x

y Peak n PENNINGTON CO SYNCLINE--Showing trace of axial plane n Battle

a o Spo Hermosa

y k C a and direction of plunge. Dashed n CUSTER CO ne a Creek Creek where approximated s C le o Bear Cr Grace B French Gulch MONOCLINE--Showing trace of axial CUSTER plane. Dashed where approximated Redbird Gillette Coolidge 45' Jewel Cave CUSTER DOME--Symbol size approximately pro- National portional to size of dome. Dome Monument STATE Fairburn Creek asymmetry indicated by arrow length n PARK o y n a

C Canyon Beaver Wind Cave Lame

Pringle National Park WYOMING Creek Wind Cave Johnny DeweyDAKOTA SOUTH Creek RIVER Red Creek Buffalo Gap 30' Hell

FALL RIVER CO H n n o o ot roo y y

B k Can HOT SPRINGS n a

Minnekahta Fall River CHEYENNE C CHEYENNE Oral Hay

Cascade Springs

Horsehead Edgemont Angostura o Creek Reservoir d RIVER Cr 43 15' oo w n o tt o Igloo C Creek Provo

Figure 14. Distribution of hydrogeologic units in the Black Hills area (modified from Strobel and others, 1999).

Geologic Framework 17