Hydrogeologic Framework of Mississippian 

Rocks in the Central Lower Peninsula 

of Michigan

By D.B. WESTJOHN and T.L. WEAVER

U.S. Geological Survey

Water-Resources Investigations Report 94-4246

Lansing, Michigan 

1996
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

Any use of trade, product, or firm name in this report is for identification 

purposes only and does not constitute endorsement by the U.S. 

Geological Survey.

For additional information 

write to:

District Chief

U.S. Geological Survey, WRD 

6520 Mercantile Way, Suite 5 

Lansing, Ml 48911

Copies of this report may be 

purchased from:

U.S. Geological Survey

Earth Science Information Center

Open-File Reports Section

Box 25286, MS 517

Denver Federal Center

Denver, CO 80225
CONTENTS

Abstract .......................................................... 1

Introduction ....................................................... 1

Geology .......................................................... 3

Coldwater Shale ................................................ 3

Marshall Sandstone .............................................. 6

Michigan Formation .............................................. 7

Hydrogeologic framework of Mississippian rocks ................................ 8

Relations of stratigraphic units to aquifer and confining units .................... 8

Delineation of aquifer- and confining-unit boundaries ......................... 9

Description of confining units and the Marshall aquifer ........................ 9

Michigan confining unit ....................................... 9

Areal extent, surface configuration, and thickness ................... 9

Hydraulic properties ..................................... 12

Use and quality of water .................................. .12

Marshall aquifer ........................................... .12

Areal extent, surface configuration, and thickness .................. .12

Hydraulic properties .................................... .15

Use and quality of water .................................. .15

Coldwater confining unit ....................................... 16

Areal extent and surface configuration ......................... .16

Hydraulic properties .................................... .16

Use and quality of water .................................. .16

Summary ........................................................ .18

References cited .................................................... .19

Appendix A: Identification and locations of geophysical and geologic logs, and generalized

hydrogeologic sections illustrating relations of aquifers and confining units ...... .25

Appendix B: Interpretation of geophysical and geologic logs ........................ .33

Appendix C: Locations of boreholes and logs ................................. .37

Appendix D: Hydraulic properties of Mississippian sandstones ...................... .43

Content* iii
FIGURES

1. Map showing Lower Peninsula of Michigan and Michigan Basin

Regional Aquifer-System Analysis study area ............................ 2

2. Map showing bedrock geology of the Lower Peninsula of Michigan .............. 4

3. Chart showing Mississippian through Pleistocene stratigraphic nomenclature,

hydrogeologic units, and rock units in the central Lower Peninsula of Michigan ...... 5

4-8. Maps showing:

4. Surface configuration of Michigan confining unit in the central Lower

Peninsula of Michigan ....................................... 10

5. Thickness of Michigan confining unit in the central Lower Peninsula of Michigan . . 11

6. Surface configuration of Marshall aquifer hi the central Lower Peninsula

of Michigan .............................................. 13

7. Thickness of Marshall aquifer in the central Lower Peninsula of Michigan ....... 14

8. Surface configuration of Coldwater confining unit hi the central Lower

Peninsula of Michigan ....................................... 17

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATED WATER-QUALITY UNITS

Multiply By To obtain

foot (ft)

foot (ft)

mile (mi)

square mile (mi2)

gallon (gal)

gallon (gal)

foot per day1 (ft/d)

foot squared per day2 (f^/d)

gallon per day per foot [(gal/d)/ft]

million gallons per day (Mgal/day)

0.3048

30.48

1.609

2.590

0.1337

0.003785

0.0003528

0.0009299

0.01242

3,785

meter 

centimeter 

kilometer 

square kilometer 

cubic foot 

cubic meter 

centimeter per second 

meter squared per day 

meter squared per day 

cubic meter per day

Sea level: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived 

from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.

Abbreviated water-quality units used in this report: Chemical concentration is given in milligrams per liter (mg/L) or micrograms per 

liter OZ/L). Milligrams per liter is a unit expressing the concentration of chemical constituents in solution as weight (milligrams) of solute 

per unit volume (liter) of water. One thousand micrograms per liter is equivalent to one milligram per liter. For concentrations less than 

7,000 mg/L, the numerical value is the same as for concentrations in parts per million.

'Hydraulic conductivity by definition is given in units of cubic feet per day per square foot [(ft'/dyft2], which is mathematically 

equivalent to feet per day (ft/d).

^ransmissivity by definition is given in units of cubic feet per day per foot [(ft3/d)/ft], which is mathematically equivalent to 

square feet per day (ft2/d).

Other abbreviations used in this report:

(cm/a) centimeters per second 

(Kv) vertical hydraulic conductivity 

(Kh) horizontal hydraulic conductivity

Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan

By D.B. Westjohn andJ.L. Weaver

Abstract

Sedimentary rocks of Mississippian age form the lower part of a regional aquifer system 

in the central Lower Peninsula of Michigan. Strata of the Michigan Formation, the Marshall 

Sandstone, and the Coldwater Shale were subdivided into an aquifer and two confining units 

on the basis of hydraulic properties. The Michigan confining unit consists of shale, limestone, dolomite, gypsum, anhydrite, and discontinuous beds of sandstone and siltstone. The 

area! extent of this unit is approximately 17,000 square miles, and thickness typically ranges 

from 300 to 400 feet. The Michigan confining unit overlies the Marshall aquifer. This aquifer consists of one or more stratigraphically continuous, permeable sandstones, which are 

hydraulically connected at the scale of the regional aquifer system. The area! extent of this 

regional aquifer is approximately 22,000 square miles, and the composite thickness of permeable sandstones that form the Marshall aquifer typically ranges from 75 to 175 feet. The 

Marshall aquifer is freshwater bearing in areas where it is in direct hydraulic connection to 

Pleistocene glacial deposits. Saline water is present in this aquifer in a zone of transition 

from freshwater to brine. The width of this transition zone typically ranges from 10 to 

30 miles, but width is as narrow as 2 to 4 miles in the northern part of the aquifer system. 

The Marshall aquifer contains brine in the central part of the basin (areal extent approximately 10,000 square miles), where it is more than 800 feet below land surface. The 

Coldwater confining unit, which underlies the Marshall aquifer, ranges from 500 to 1,300 

feet in thickness. This confining unit forms the basal part of the regional aquifer system, and 

it consists mostly of shale.

INTRODUCTION

Bedrock units of Mississippian through Jurassic age and unconsolidated Pleistocene glacial 

deposits form a regional system of aquifers and confining units in the central Lower Peninsula of 

Michigan. The areal extent of this aquifer system is approximately 22,000 mi2 (fig. 1). This aquifer 

system was studied during the period from 1986 through 1994 as part of the Regional Aquifer-System 

Analysis (RASA) program (Mandle, 1986) of the U.S. Geological Survey (USGS). The Michigan 

Basin RASA project is one of 28 USGS hydrogeologic investigations of regional aquifer systems of 

the United States (Weeks and Sun, 1987).

The purposes of this report are to describe the hydrogeology and hydraulic properties of geologic units of Mississippian age in the Michigan Basin, and to publish maps that delineate surface configuration and thickness of aquifer-system units. Descriptions of hydrogeologic units are summarized 

on the basis of published information and data collected as part of the Michigan Basin RASA

Introduction 1
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EXPLANATION

[::: :::::: :: :: :: :: :: ::: :: :i STUDY AREA

/5 SAGINAW LOWLANDS

 CONTACT OF MISSISSIPPIAN COLDWATER SHALE 

AND MARSHALL SANDSTONE. AND BOUNDARY 

OF STUDY AREA

Figure 1 . Lower Peninsula of Michigan and Michigan Basin Regional Aquifer-System Analysis study area.

2 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
investigation. Maps that delineate aquifer- and confining-unit boundaries were prepared by use of 

geophysical and geologic logs of oil, gas, and water wells.

GEOLOGY

The Michigan Basin is an intracratonic depression that contains more than 17,000 ft of sedimentary rocks and unconsolidated sediments. The stratigraphic record is nearly complete from sedimentary rocks of Precambrian age at the base of the stratigraphic sequence through Jurassic red beds, 

with the exception that rocks of Triassic age are not present in the basin. Because Pleistocene glacial 

deposits cover bedrock in most areas, knowledge of bedrock geology is almost entirely from geophysical and geologic logs of drill holes.

Geologic units that form the Michigan Basin regional aquifer system are Early Mississippian 

through Jurassic age bedrock units, and unconsolidated glacial deposits of Pleistocene age. The 

aquifer system consists of six formations that have formal stratigraphic names and three geologic 

units that have informal names (figs. 2 and 3). Formally named units of Mississippian age are the 

Coldwater Shale, the Marshall Sandstone, the Michigan Formation, and the Bayport Limestone. 

Formally named units of Pennsylvanian age are the Saginaw Formation and the Grand River 

Formation. Geologic units that have informal names are the Parma sandstone (member of the 

Saginaw Formation), Jurassic red beds and Pleistocene glacial deposits.

Reports by Westjohn and Weaver (1994, 1996a) and Westjohn and others (1994) provide geologic descriptions and contain bibliographies of geological investigations of Late Mississippian and all 

younger geologic units, which form the upper part of the regional aquifer system. The geologic setting, stratigraphic relations, and hydrogeologic framework of the Coldwater Shale, Marshall Sandstone, and Michigan Formation, which form the lower part of the aquifer system, are described in 

this report. The stratigraphic relations of Mississippian bedrock units and overlying geologic deposits 

are shown in generalized hydrogeologic sections A-A' and B-B' (Appendix A).

Coldwater Shale

The Coldwater Shale is primarily gray to dark gray shale. Other lithologies include red fossiliferous or nonfossiliferous shale (informally called Coldwater red rock; see Michigan Geological Survey, 1964), carbonate (limestone or dolomite, particularly in the western half of the basin), siltstone, 

and sandstone. In the northeastern part of the basin, natural-gas-bearing sandstones in the Coldwater 

Shale have been informally named the Weir sand (Michigan Geological Survey, 1964).

The source area for the Coldwater Shale and overlying clastic sedimentary rocks of Mississippian age is inferred to be in southeastern Ontario (Potter and Pryor, 1961). In the Thumb Area 

(fig. 1), which is near the inferred sediment source, the upper part of the Coldwater Shale consists of 

intercalated shale, siltstone, and sandstone. The Coldwater sequence in this area is interpreted to be 

part of a southwest-prograded-deltaic complex. Cumulative thickness of sandstone beds in the 

Coldwater Shale ranges from 100 to 200 ft in the Thumb Area (fig. 1), but sandstone beds thin to the 

southwest and are absent in most of the western part of the Lower Peninsula (Cohee, 1979, p. 54). 

Total thickness of the Coldwater Shale ranges from 500 ft in the west (Cohee, 1979) to more than 

1,300 ft in the east (John Esch, Michigan Department of Natural Resources, written commun., 1994).

Topics of previous investigations of the Coldwater Shale have included economic geology 

(Cohee and others, 1951; Newcombe, 1933), general geology (Dorr and Eschman, 1970; Ells, 1979;

Geology 3
86* 85* 84* 83*

45'

44'

43'

42'

Base from U.S. Geological Survey 1:500,000 

state base map. 1970

FORMATION 

"Red Beds"

20

I

40

I

60 MILES

I

EXPLANATION

Grand River and Saginaw Formations, 

Parma Sandstone, and Bayport 

Limestone

Michigan Formation

Marshall Sandstone 

Coldwater Shale

Ellsworth and Antrim Shales and 

older rocks

I I I

20 40 60 KILOMETERS

PERIOD

 JURASSIC

PENNSYLVANIA

 AND LATE 

MISSISSIPPIAN

EARLY

 MISSISSIPPIAN 

AND OLDER

Figure 2. Bedrock geology of the Lower Peninsula of Michigan. (Modified from Western Michigan 

University, 1981, pi. 12; and from Westjohn and others, 1994.)

Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigen
Hydrogeologic unit 

(general thickness range)

Glacial lacustrine confinin 

unit (0-100 ft)

Jurassic "red beds

confining unit

(0-150 ft)

Parma-Bay port aquifer 

(50-200 ft)

Michigan confining unit 

(50-400 ft)

Coldwater confining unit 

(500-1,300 ft)

EXPLANATION 

Glacial lacustrine sediments 

Glaciofluvial sand and gravel

Glacial till

Shale

Sandy or silty shale

Sandstone

Argillaceous or shaly sandstone

Limestone

Argillaceous or shaly limestone

Cherty limestone

Dolomite 

(Same variations as limestone)

Coal beds

Anhydrite or gypsum 

Erosional surface

Figure 3. Mississippian through Pleistocene stratigraphic nomenclature, hydrogeologic units, and rock 

units in the central Lower Peninsula of Michigan. (Modified from Michigan Geological Survey, 1 964.)

Geology 5
Wooten, 1951), hydrogeology (Mandle and Westjohn, 1989; Westjohn and Weaver, 1994), paleontology (Driscoll, 1969), paleotectonic setting (Cohee, 1979), palynology (See, 1980), and sedimentology 

and stratigraphy (Chung, 1973; Harrell and others, 1991; Kropschot, 1953; Lilienthal, 1978; Potter 

and Pryor, 1961; Shaver, 1985; Tarbell, 1941). Martin and Straight (1956) provide a bibliography of 

early investigations and a historic account of development of stratigraphic nomenclature for the Coldwater Shale.

Marshall Sandstone

The Marshall Sandstone is the formal stratigraphic name for a sequence of sedimentary rocks 

between the Coldwater Shale and the Michigan Formation (fig. 3). Sandstone constitutes only part of 

the formation. Limestone, dolomite, siltstone, and shale are interbedded with sandstones of the 

Marshall sedimentary sequence in different parts of the basin. Two relatively thick, stratigraphically 

continuous sandstones constitute most of the Marshall Sandstone (formation name) in most areas. The 

upper sandstone is formally named the Napoleon Sandstone Member. However, use of this formal 

name is somewhat obscure, because other strata of the Marshall sedimentary sequence have not been 

formally named (hence, the Marshall Sandstone with formation rank has only one member). Typically, when the Marshall Sandstone is subdivided, the informal stratigraphic term "lower Marshall 

sandstone" and the formal name Napoleon Sandstone (also commonly called the upper Marshall sandstone) are used to identify sandstones that are separated by other lithologies. These formal and 

informal names are used in this report where stratigraphic relations of different sandstone units are the 

topic of discussion.

Examination of geophysical logs shows that lithofacies trends of strata are mappable within the 

Marshall Sandstone. A description of the vertical and lateral lithofacies trends, which is useful in 

characterization of hydrogeology of Mississippian rock units (see later section) is given on the basis of 

interpretation of geophysical logs.

Everywhere in the Michigan Basin where the Marshall Sandstone is present, the basal part of the 

formation consists of 30 to 125 ft of fine-grained micaceous sandstone or micaceous siltstone. This 

basal unit of the Marshall sequence has a distinctive shaly-sand trace (Asquith and Gibson, 1982, 

p. 31 and p. 102) on gamma-ray and spontaneous potential geophysical logs (Appendix B).

The basal micaceous sandstone/siltstone of the Marshall sequence is overlain by fine- to mediumgrained sandstone, which is typically 50 to 125 ft thick. This fine- to medium-grained sandstone is 

referred to as the "lower Marshall sandstone" by geologists that divide the formation into members 

(Ells, 1979; Harrell and others, 1991; Martin, 1936). In some areas of the basin, these two units 

constitute the entire formation.

In areas where a second sandstone is present and is considered to be part of the Marshall sedimentary sequence, this sandstone is commonly called the "Napoleon Sandstone Member" (Harrell and 

others, 1991; Martin, 1936; Michigan Geological Survey, 1964). The Napoleon Sandstone has the 

same range of thickness as the lower Marshall sandstone, and it is not possible to differentiate these 

sandstones on the basis of lithologic characteristics (Monnett, 1948).

Generally, where the lower sandstone is thick, the upper sandstone is thin, and vice versa. 

Lower and upper sandstones are separated by strata whose facies relations are complex. In some 

areas, particularly along a 15-mi-wide corridor (extending northwest) from Livingston County to 

Newaygo County (fig. 1), the lower sandstone is overlain by 15 or more ft of shale, and this shale is 

overlain by 30 or more ft of siltstone (see example log, Appendix B). On either side of this corridor, 

an intercalated sequence of carbonate, siltstone, and shale, and (or) evaporite separates the upper

Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
sandstone from the lower sandstone. Strata between these sandstones interfinger, and they seem to be 

facies assemblages of time-stratigraphic equivalents, which were deposited in sub-basins that 

developed during late Marshall sedimentation.

Topics of previous investigations of Mississippian sandstones in the Michigan Basin have 

included economic geology (Ball and others, 1941; Cohee and others, 1951; Hake, 1938; Hale, 1941; 

Hard, 1938; Harrell and others, 1991; Newcombe, 1933), general geology (Dorr and Eschman, 1970; 

Ells, 1979), hydrogeology (Mandle and Westjohn, 1989; Westjohn and Weaver, 1994), mineralogy 

and petrology (Stearns, 1933; Stearns and Cook, 1931; Zacharias and others, 1994), paleotectonic 

setting (Cohee, 1979), paleontology (Driscoll, 1965, 1969) palynology (See, 1980), stratigraphy 

(Harrell and others, 1991; Lilienthal, 1978; Monnett, 1948; Pawlowicz, 1969; Shaver, 1985), and 

sedimentology (Harrell and others, 1991; O'Hara, 1954; Potter and Pryor, 1961; Rorick, 1983).

Michigan Formation

The Michigan Formation is an interbedded sequence of shale, limestone, dolomite, gypsum or 

anhydrite, and discontinuous beds of siltstone and sandstone (listed in order of decreasing abundance). 

The cumulative thickness of all lithologies is typically 300 to 400 ft (Harrell and others, 1991). Geophysical logs were used by RASA investigators to delineate boundaries of the Michigan Formation. 

Examination of these logs shows that thickness of individual strata typically is less than 10 ft, and the 

thin-bedded character and marked contrast in lithology results in erratic changes in geophysical-log 

traces (Appendix B). Generally, 6 to 10 gypsum beds are intercalated with shale and (or) limestone 

and (or) dolomite. In most areas of the basin, a sequence of three gypsum beds (commonly referred 

to as "triple gyp," Lilienthal, 1978, p. 5) shows as a distinctive signature on electrical-resistivity logs. 

These distinctive gypsum beds are separated from the top of the Marshall Sandstone by various thicknesses of Michigan Formation strata, depending on location in the basin (110 to 140 ft in west, 220 ft 

in the east, more than 300 ft in the north, unknown in the south). Gypsum beds generally are thickest 

(some beds 20 to 30 ft in thickness) in the eastern and northeastern parts of the basin, and these relatively thick beds underlie the "triple gyp" strata.

In many areas of the Michigan Basin, sandstones at the base of the Michigan Formation were 

exploited for natural gas. There has been substantial debate regarding the origin and stratigraphic 

affinity of natural-gas-bearing sandstones deposited during the interval between Early and Late Mississippian time. Some geologists argue that natural-gas-bearing sandstones that are areally extensive 

interfinger with the Napoleon Sandstone and are part of the late Marshall sedimentary sequence (Ells, 

1979; Harrell and others, 1991; Thomas, 1931). Analysis of geophysical data by RASA investigators 

supports that interpretation. One factor that complicates interpretation of stratigraphy, is that sandstones of Mississippian age were deposited in two very different sedimentary environments. One depositional environment produced areally extensive blanket sandstones1 , in which natural gas was 

contained along the closures of north- to northwest-trending anticlines. The other depositional environment produced elongate, laterally discontinuous sandstone bodies that contained natural gas. 

These discontinuous sandstones may have formed as offshore sandbars, as suggested by Ball and 

others (1941). Typically, these elongate discontinuous sandstone bodies are thin (usually less than 

10 ft, but as thick as 30 ft) and intercalated with evaporite, dolomite, limestone, and shale.

Blanket sand, as defined by Bates and Jackson (1987, p. 74), is a "deposit of sand or sandstone of unusually wide 

distribution, typically an orthoquartzitic sandstone deposited by a transgressive sea advancing for a considerable distance over 

a stable shelf area."

Geology 7
The common practice during the early 1930's through the 1950's, a period of considerable 

exploration for natural gas in Mississippian sandstones, was to name any gas-bearing sandstone the 

"Michigan stray sandstone" (Newcombe, 1933, p. 196). The problem with this informal stratigraphic 

name is that natural gas was discovered in multiple, stacked horizons of discontinuous sandstones, as 

well as in blanket sandstones. Hard (1938) constructed fence diagrams that show relations of discontinuous sandstone bodies to blanket sandstones (Napoleon and lower Marshall sandstone). His diagrams illustrate as many as three separate "stray sandstone" horizons above the Napoleon Sandstone. 

For purposes of characterization of hydrogeologic framework of the regional aquifer system, RASA 

investigators consider blanket sandstones to be part of the Marshall sedimentary sequence; elongate 

discontinuous sandstone bodies are considered to be part of the Michigan Formation.

Previous investigations of the Michigan Formation focused on economic geology (Briggs, 1970; 

Cohee and others, 1951; Hake, 1938; Hard, 1938; Harrell and others, 1991; Newcombe, 1933), 

general geology (Dorr and Eschman, 1970; Ells, 1979), hydrogeology (Mandle and Westjohn, 1989; 

Westjohn and Weaver, 1994), and sedimentology and stratigraphy (Cohee, 1965, 1979; Barrel and 

others, 1991; Lilienthal, 1978; McGregor, 1954; Moser, 1963; Olszewski, 1978; Shaver, 1985). 

Extensive bibliographies of previous investigations of the Michigan Formation are included in publications by Harrell and others (1991), Martin and Straight (1956), and Moser (1963).

HYDROGEOLOGIC FRAMEWORK OF MISSISSIPPIAN ROCKS

The stratigraphic units previously discussed are divided into three hydrogeologic units (fig. 3): 

the Michigan confining unit, the Marshall aquifer, and the Coldwater confining unit. Explanations of 

the relations of stratigraphic units to hydrogeologic units, and methods used to delineate boundaries of 

hydrogeologic units are followed by discussion of the area! extent, thickness, surface configuration, 

hydraulic properties, and use and quality of water of each of these units.

Relations of Stratigraphic Units to Aquifer and Confining Units

Relations of stratigraphic names to hydrogeologic nomenclature established for the Michigan 

Basin RASA study are shown in figure 3. Also shown are lithologic constituents of formations and 

thicknesses of the Marshall aquifer and Michigan and Coldwater confining units. Boundaries of these 

units were delineated on the basis of hydraulic properties. Thus, a hydrogeologic unit may consist of 

part or all of a formation. For example, sandstone is present at or near the base of the Mississippian 

Michigan Formation in many areas of the basin. Some previous investigators suggest that these sandstones should be assigned to the Michigan Formation (for example, Hake, 1938; Hard, 1938; 

Michigan Geological Survey, 1964). Others interpret stratigraphically continuous sandstones to be 

part of the Marshall sedimentary sequence (Ells, 1979; Harrell and others, 1991). It is generally not 

possible to distinguish these sandstones at the base of the Michigan Formation from underlying Mississippian sandstones (Napoleon or Marshall Sandstone; Monnett, 1948). Regardless of stratigraphic 

relations, relatively thick, blanket-type, stratigraphically continuous Mississippian sandstones between 

the Coldwater Shale and Michigan Formation are assumed to be hydraulically connected at the scale 

of the RASA study area, and collectively they form the Marshall aquifer (fig. 3). In contrast, the 

Mississippian Coldwater Shale (formal stratigraphic nomenclature) and Coldwater confining unit 

(hydrogeologic name) refer to the same geologic unit (fig. 3). The Coldwater Shale consists mostly 

of shale, and this formation forms a confining unit throughout the study area. Stratigraphic names

Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
and hydrogeologic unit nomenclature are used in this report, depending on whether the topic of discussion is geology or hydrogeology.

Delineation of Aquifer- and Confining-Unit Boundaries

Of the numerous detailed studies of geologic units in the Michigan Basin, most have focused on 

stratigraphy, sedimentology, and depositional environment (Alien and others, 1916; Cohee and others, 

1951; Lane, 1902, 1905; Martin, 1936; Martin and Straight, 1956; Milstein, 1987; Newcombe, 1933; 

O'Hara, 1954; Moser, 1963; Potter and Pryor, 1961; Rorick, 1983; Winchell, 1869). Maps 

generated as part of these studies delineate boundaries or thicknesses of formations. A literature 

search done as part of the RASA investigation failed to locate maps that depict boundaries of hydrogeologic units. Thickness and surface-configuration maps included with this report delineate 

aquifer- and confining-unit boundaries rather than contacts of different stratigraphic units.

Geophysical logs of oil and gas wells were used to establish hydrogeologic characteristics and 

map hydrostratigraphic units in the central part of the basin. In areas where geophysical logs are 

sparse or nonexistent, information from geologic logs of oil, gas, and water wells was used to delineate aquifer- and confining-unit boundaries. In Appendix B, example geophysical logs are provided, 

and methods used to delineate aquifer- and confining-unit boundaries by interpretation of geophysical 

and geologic logs are described.

Description of Confining Units and the Marshall Aquifer 

Michigan Confining Unit

The Michigan confining unit is the composite of all confining-unit lithologies of the Michigan 

Formation. This confining unit separates the Parma-Bayport aquifer from the underlying Marshall 

aquifer (fig. 3). The Michigan confining unit consists of shale, carbonate, evaporite, and thin, laterally discontinuous siltstone and sandstone lenses. The sandstone/siltstone lenses are intercalated with 

evaporite, shale, dolomite, and limestone. These intercalated units probably do not contribute a significant quantity of ground water to the regional flow system.

Areal Extent, Surface Configuration, and Thickness

The Michigan confining unit is present in most of the RASA study area, and its area! extent is 

approximately 17,000 mi2 . Surface configuration of this confining unit is shown in figure 4. Altitudes of the top of the Michigan confining unit are lowest in the north-central part of the study area, 

where altitudes are more than 200 ft below sea level. The surface of the confining unit is highest in 

the south and east, where altitudes are approximately 900 ft and 600 ft above sea level, respectively. 

In the west and north, altitudes of the top of the confining unit generally range from 300 to 400 ft 

above sea level.

The Michigan confining unit generally thickens from south to north (fig. 5). In the northwestern 

part of the study area, the confining unit typically ranges from 300 to 400 ft in thickness. The unit 

thins to 100 ft in the south and east. In the northeastern part of the mapped area, the unit is less 

than 50 ft thick in places. The locations of boreholes and logs used to construct surfaceconfiguration and thickness maps of the Michigan confining unit are shown in Appendix C.

Hydrogeologic Framework of Mississippian Rocks 9
86* 85* 84* 83'

45'

44'

43'

42'

BOUNDARY OF RASA 

STUDY AREA

SUBCROP OF ! 

MICHIGAN FORMATION

/ SUBCROP OF 

/ PENNSYLVANIAN ROCKS

Base from U.S. Geological Survey 1:500,000 

state base map, 1970 20 

I

40 60 MILES

I T I 

20 40 60 KILOMETERS

EXPLANATION

-goo- STRUCTURE CONTOUR Shows altitude of top of Michigan 

confining unit. Dashed where approximately 

located. Hachures indicate depression. 

Contour interval 100 feet. Datum 

is sea level

Figure 4. Surface configuration of Michigan confining unit in the central Lower Peninsula of Michigan.

10 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
86° 85° 84° 83*

45"

44°

43'

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-^

BOUNDARY OF RASA 

STUDY AREA

PENNSYLVANIAN ROCKS-£

/ SUBCROP OF 

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^

Base from U.S. Geological Survey 1:500,000 

state base map, 1970 20 

I

40 60 MILES

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20 40 60 KILOMETERS

EXPLANATION

-100 - LINE OF EQUAL THICKNESS Shows thickness of 

Michigan confining unit. Dashed where 

approximately located. Hachures 

indicate depression. Contour interval 

50 feet. Datum, is sea level

Figure 5. Thickness of Michigan confining unit in the central Lower Peninsula of Michigan.

Hydrogeologic Framework of Mwctoippian Rocks 11
Hydraulic Properties

No hydraulic-property data are available for the Michigan confining unit. Evidence that the unit 

functions as a confining unit are the wide-spread reservoirs of natural gas trapped in sandstones below 

gypsum, anhydrite, limestone, or dolomite beds of the Michigan confining unit (Rawlins and 

Schellhardt, 1936).

Use and Quality of Water

Few water wells are completed in the Michigan Formation, because potable water is available 

from overlying glaciofluvial and Saginaw aquifers. In areas where the Michigan Formation is in 

direct hydraulic connection with glacial deposits, some water wells for domestic supply are completed 

in the confining unit. Dissolved-solids concentration of ground water sampled from wells completed 

in the Michigan confining unit in subcrop areas ranges from 240 to 6,800 mg/L, and predominant solutes are typically calcium sulfate or calcium bicarbonate (Dannemiller and Baltusis, 1990).

Marshall Aquifer

The Marshall aquifer consists of all blanket-type sandstones of Mississippian age, but it does not 

include thin, laterally discontinuous sandstone lenses intercalated with typical Michigan Formation 

lithologies. The Marshall aquifer consists of one or more permeable sandstones that are assumed to 

be hydraulically connected at the scale of the regional aquifer system. Delineation of permeable sandstones by use of geophysical logs is described in Appendix B, and by Westjohn (1989, 1994).

Area) Extent, Surface Configuration, and Thickness

The Marshall aquifer is laterally continuous throughout the RASA study area, and the area! 

extent of this aquifer is approximately 22,000 mi2 . Surface configuration of the Marshall aquifer is 

shown on figure 6. Altitudes of the top of the aquifer are lowest in the central part of the basin, 

where the top of the unit is more than 600 ft below sea level. The top of the aquifer is highest 

toward the boundary of the study area. In the south, altitude of the top of the aquifer is more than 

800 ft above sea level. Highest altitudes range from 300 to 400 ft in the west and from 500 to 700 ft 

above sea level in the north. Altitudes in the east generally range from 500 to 600 ft above sea level. 

Locations of boreholes and logs used to construct the surface-configuration map of the Marshall aquifer are shown in Appendix C.

Only permeable sandstones are considered to constitute aquifer material, and all other lithologies 

were excluded in the preparation of the Marshall aquifer thickness map (fig. 7). Thickness of the 

Marshall aquifer is 75 to 125 ft in most of eastern and southern parts of the RASA study area. The 

aquifer thins to approximately 75 ft along a northwest-trending corridor from Livingston County to 

Newaygo County. The aquifer is more than 200 ft thick in the northwestern part of the study area 

(Wexford County and Osceola County, figs. 1 and 7). The locations of boreholes, gamma-ray logs, 

and electrical-resistivity logs used to construct the thickness map of the Marshall aquifer are shown in 

Appendix C.

12 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
86'

45'

44'

43' -

42'

85*

~i ;

84° 83°

s

BOUNDARY OF RASA 

STUDY AREA

SUBCROP OF 

/ MICHIGAN FORMATION

Bose from U.S. Geological Survey 1:500,000 

state base map, 1970 20

I

40 

I

60 MILES

I I

EXPLANATION

-goo - STRUCTURE CONTOUR Shows altitude of top of Marshall 

aquifer. Dashed where approximately 

located. Hachures indicate depression. 

Contour interval 100 feet. Datum 

is sea level

Figure 6. Surface configuration of Marshall aquifer in the central Lower Peninsula of Michigan.

Hydrogedogic Framework of Mwctoippian Rocks 13
86*

45'

43'

42*

85* 84* 83*

/ »-' . '? 

f" /'*// BOUNDARY OF RASA 

j v'y STUDY AREA

^ n in il-iiii r^

/ E

Base from U.S. Geological Survey 1:500,000 

state base map, 1970 20 

I

40 eo MILES 

_i____I I r r^

20 40 60 KILOMETERS

EXPLANATION

-100- LINE OF EQUAL THICKNESS Shows thickness 

of Marshall aquifer. Dashed where 

approximately located. Hachures 

indicate depression. Contour interval 

50 feet. Datum is sea level

Figure 7. Thickness of Marshall aquifer in the central Lower Peninsula of Michigan.

14 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
Hydraulic Properties

Hydraulic properties of the Marshall aquifer have been interpreted from aquifer tests at Battle 

Creek and Jackson, two large municipalities in the southern part of the study area (fig. 1). The aquifer is highly productive in these areas, and each municipality withdraws more than 10 Mgal/d of 

ground water (Grannemann and others, 1985). Large ground-water withdrawals are possible at these 

sites because the Marshall aquifer is highly fractured. Transmissivities determined from aquifer tests 

at the Verona well field in Battle Creek, Mich. (fig. 1) range from 3,000 to 27,000 ft2/d (Grannemann and Twenter, 1985, p. 25). These transmissivities are based on constant hydraulic conductivities of 150 and 550 ft/d. Transmissivities of the Marshall aquifer determined from aquifer tests at 

the Jackson well field range from 7,500 to 29,000 ft2/d (George Econ, Jackson Community College, 

written commun., 1993).

In other areas of the basin, the Marshall aquifer is substantially less productive. Transmissivities 

determined from aquifer tests in Huron County (fig. 1) range from 7 to 50 ft2/d, and hydraulic conductivities range from 0.2 to 1.5 ft/d (Sweat, 1992). Similar ranges of hydraulic properties were 

derived from double-packer aquifer tests done as part of the Michigan Basin RASA study (Westjohn, 

1993). Analysis of aquifer tests of the Marshall aquifer in three counties (Muskegon, Genesee, and 

Eaton Counties; fig. 1) indicate a small range of transmissivities (10 to 37 ft2/d) and hydraulic conductivities (0.2 to 0.5 ft/d).

Hydraulic properties of sandstone cores sampled from the Marshall aquifer were measured as 

part of the Michigan Basin RASA investigation. Porosity was measured of 63 sandstone cores, vertical hydraulic conductivity was measured of 43 samples, and horizontal hydraulic conductivity was 

measured of 20 samples. The porosity and hydraulic-conductivity data are summarized in 

Appendix D.

The suite of sandstone specimens selected for laboratory measurements of hydraulic properties 

are well cemented, unfractured sandstones, so the measurements reflect matrix-controlled hydraulic 

properties. The upper range of matrix-controlled hydraulic conductivities measured of cores (1.3 to 

1.8 ft/d) is similar to higher hydraulic conductivities determined from aquifer tests in several counties. 

These similarities indicate that fractures are absent in the Marshall aquifer at these localities and that 

ground-water flow in the aquifer is dominated by matrix-hydraulic properties of sandstones.

Use and Quality of Water

The Marshall aquifer is a source of water supply in more than 40 municipalities in the southern 

and eastern parts of the study area (Baltusis and others, 1992). Water quality in the Marshall aquifer 

is suitable for most uses in subcrop areas, where this unit is in direct hydraulic connection with 

glacial deposits (Westjohn, 1994a; Westjohn and Weaver, 1996b). Wells completed in the Marshall 

aquifer in parts of at least 21 counties in the study area produce water with dissolved solids concentrations less than 1,000 mg/L (Dannemiller and Baltusis, 1990). Depths of wells that produce freshwater from the Marshall aquifer are less than 400 ft, except in five counties (Arenac, Genesee, 

Lapeer, Livingston, and Tuscola, see fig. 1), where wells 400 to 432 ft deep yield freshwater.

Down regional dip from subcrop areas, where the Marshall aquifer is overlain and confined 

(partially or completely) by the Michigan confining unit, salinity of ground water increases. The 

width of the transition zone where saline water is present in the aquifer ranges from 10 to 30 mi in 

most of the study area but is as narrow as 2 to 4 mi in the northwest (Westjohn, 1989; Westjohn and 

Weaver, 1996b). The areal extent of the brine-bearing part of the Marshall aquifer is approximately

Hydrogeologic Framework of Miccwcippian Rocks 15
10,000 mi2 (Westjohn, 1989; Westjohn and Weaver, 1996b). Dissolved-solids concentration as large 

as 337,000 mg/L is found in the central part of the basin (Western Michigan University, 1981, 

pi. 24).

Coldwater Confining Unit

The Coldwater confining unit forms the base of the regional aquifer system. This confining unit 

consists mostly of shale; siltstone, sandstone, limestone, and dolomite constitute part of this hydrogeologic unit in some areas of the basin. The Coldwater confining unit is approximately 1,300 ft 

thick in the eastern part of the study area (John Esch, Michigan Department of Natural Resources, 

written commun., 1994), but it thins to approximately 500 ft hi the western part (Cohee, 1979). 

Although the cumulative thickness of sandstone and siltstone lenses ranges from 100 to 200 ft hi parts 

of the Thumb Area (fig. 2; Cohee, 1979), these lenses of sandstone and siltstone are laterally discontinuous and are separated from the overlying Marshall aquifer by shale. These sandstone and siltstone 

lenses probably do not contribute a significant amount of ground water to the regional-flow system.

Areal Extent and Surface Configuration

The area! extent of the Coldwater confining unit is more than 32,000 mi2 . This unit extends 

south into northern Indiana and Ohio. The subcrop of this confining unit also extends west under 

Lake Michigan and east under Lake Huron. The surface configuration of the Coldwater confining 

unit (fig. 8) is similar to surface configurations of the Michigan confining unit (fig. 4) and Marshall 

aquifer (fig. 6). Altitudes of the top of the Coldwater confining unit are more than 800 ft below sea 

level in the central part of the Michigan Basin. Altitudes are highest hi the northern and southern 

parts of the aquifer system (700 to 800 ft), lowest hi the west (300 ft), and intermediate hi the east 

(600 ft). The locations of boreholes and logs used to construct the surface-configuration map of the 

Coldwater confining unit are shown in Appendix C.

Hydraulic Properties

No data on hydraulic properties are known to have been published for the Coldwater confining 

unit. Laboratory measurements of porosity and hydraulic conductivity have been made of cores of 

the basal part of the Marshall sedimentary sequence (Appendix D). Vertical and horizontal hydraulic 

conductivities of these rocks are generally two to three orders of magnitude less than those of overlying permeable sandstones (either lower Marshall sandstone or Napoleon Sandstone). Shales that 

form the bulk of the Coldwater confining unit are assumed to have lower hydraulic conductivities than 

the micaceous sandstones/siltstones at the base of the Marshall aquifer; hence, the Coldwater confining unit probably does not contribute a significant amount of ground water to the regional-flow 

system.

Use and Quality of Water

Water wells are rarely completed in the Coldwater confining unit because potable water is generally available in overlying glacial deposits or bedrock aquifers. Water wells are occasionally completed in the Coldwater confining unit in areas where it subcrops beneath glacial drift (southern 

subcrop area, fig. 2). In many counties in the southern part of the State where the Coldwater

16 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
86*

45*

44'

43*

42'

85* 84* 83*

SUBCROP OF 

COLDWATER SHALE

N

*!

BOUNDARY OF RASA 

STUDY AREA

i___- -ILAKE 

ERIE

Base from U.S. Geological Survey 1:500.000 

state base map, 1970 20

I

40 

I

60 MILES 

I

EXPLANATION

-BOO- STRUCTURE CONTOUR Shows altitude of top of Coldwater 

confining unit. Dashed where approximately 

located. Hachures indicate depression. 

Contour interval 100 feet. Datum 

is sea level

Figure 8. Surface configuration of Coldwater confining unit in the central Lower Peninsula of Michigan.

Hydrogeologic Framework of MtoiMippian Rocks 17
confining unit sub crops, glacial deposits are predominantly clay-rich tills, and glaciofluvial deposits or 

other aquifer material of glacial origin are absent. In these areas, the Coldwater confining unit is 

commonly explored for potential development of water supply. In some places, the Coldwater confining unit will produce small quantities of water of acceptable quality for domestic supply; typically, 

however, ground water contains a high concentration of dissolved solids (greater than 1,000 mg/L) 

(Mark Breithart, Michigan Department of Public Health, oral commun., 1994). In the Thumb Area 

of Michigan (fig. 1), ground water sampled from six wells completed in the Coldwater confining unit 

had concentrations of dissolved solids that ranged from 17,700 to 39,000 mg/L (Sweat, 1992, p. 73).

SUMMARY

Sedimentary rocks of Mississippian age form the lower part of a regional system of aquifers and 

confining units in the central part of the Lower Peninsula of Michigan. Strata of the Michigan Formation, the Marshall Sandstone, and Coldwater Shale were subdivided into an aquifer and two confining units on the basis of hydraulic properties. Surface-configuration and thickness maps of these 

aquifer-system units were prepared by USGS hydrogeologists, to aid in characterization of the hydrogeologic framework of the Michigan Basin RASA study area. These maps delineate boundaries of 

aquifer-system units for purposes of numerical simulation ground-water flow.

The Michigan confining unit consists of shale, limestone, dolomite, gypsum/anhydrite, and isolated lenses of siltstone and sandstone. This confining unit is laterally continuous, typically ranges 

from 300 to 400 ft in thickness, and has an areal extent of about 17,000 mi2 .

The Michigan confining unit overlies the Marshall aquifer, which consists of one or more stratigraphically continuous permeable sandstones. In areas where the Marshall aquifer consists of two or 

more sandstones, these permeable strata typically are separated by beds of siltstone, shale and (or) 

carbonate. It is assumed that areally extensive Mississippian sandstones that form the Marshall aquifer are hydraulically connected at the scale of the regional aquifer system, and this aquifer unit forms 

a single layer for purposes of numerical simulation of ground-water flow. The composite of permeable sandstones that form the Marshall aquifer typically ranges from 75 to 125 ft in thickness, and the 

areal extent of this regional aquifer is about 22,000 mi2. The Marshall aquifer is freshwater bearing 

hi areas where it subcrops and is in direct hydraulic connection to Pleistocene glacial deposits. Down 

regional dip and away from subcrop areas, where the Marshall aquifer is partially or entirely confined 

by the Michigan confining unit, salinity of ground water in this aquifer progressively increases. The 

transition zone from freshwater to brine in the Marshall aquifer is about 20 mi hi width in the 

southern part of the aquifer system, and approximately 10 mi in width in the northern part. The 

Marshall aquifer contains brine in the central part of the basin (areal extent about 10,000 mi2), where 

this unit is more than 800 ft below land surface.

The Coldwater confining unit underlies the Marshall aquifer and forms the basal part of the 

regional aquifer system. This confining unit is about 1,100 ft in thickness in most of the eastern part 

of the aquifer system, but it thins to about 500 ft hi the western part of the mapped area. The Coldwater confining unit consists mostly of shale, but carbonate beds constitute part of the confining unit 

in west-central part of the basin. There are sandstone/siltstone lenses interbedded with shale of the 

Coldwater confining unit in the east-central part of the basin. The composite thickness of these more 

permeable strata ranges from 100 to 200 ft in the Thumb area of the State, but these beds are 

separated from the overlying Marshall aquifer by shale. Interpretations of geophyiscal logs indicate 

that siltstone and sandstone beds are thin and laterally discontinuous; they probably do not contribute 

a substantial amount of ground water to the regional-flow system.

18 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
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20 Hydrogeologic Framework of Mississippian Rocks 

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22 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
APPENDIXES

APPENDIX A. IDENTIFICATION AND LOCATIONS OF GEOPHYSICAL 

AND GEOLOGIC LOGS, AND GENERALIZED HYDROGEOLOGIC 

SECTIONS ILLUSTRATING RELATIONS OF AQUIFER-SYSTEM UNITS

CONTENTS

Table Al. Identification of geophysical and geologic logs used in the construction of

hydrogeologic section A-A', Muskegon County to Crawford County, Michigan .... 27

Table A2. Identification of geophysical and geologic logs used in the construction of

hydrogeologic section B-B', Wexford County to Shiawassee County, Michigan .... 28

Figure Al. Map showing location of geophysical and geologic logs used in the construction

of hydrogeologic sections A-A' and B-B', central Lower Peninsula of Michigan .... 29

Figure A2. Generalized hydrogeologic section A-A' showing stratigraphic relations of 

Mississippian and younger geologic units, Muskegon County to 

Crawford County, Michigan .................................... 30

Figure A3. Generalized hydrogeologic section B-B' showing stratigraphic relations of 

Mississippian and younger geologic units, Wexford County to 

Shiawassee County, Michigan ................................... 31

Appendix A 25

Table A1. Identification of geophysical and geologic logs used in the construction of hydrogeologic section 

A-A', Muskegon County to Crawford County, Michigan

[Permit numbers are assigned to oil and gas wells by Michigan Department of Natural Resources; dashes indicate that no permit number 

was issued or that well was used for purposes other than oil or gas exploration or production. U.S. Geological Survey (USGS) identifiers 

are numbers assigned to logs on file at USGS, indicating county where well is located, type of well, and type of log]

Permit 

number

18227

1499

217

16718

13520

13719

13264

13146

16245

16305

16005

34622

11775

9806

12018

11061

16335

12868

10498

31670

10795

11946

14759

15433

16985

15702

39826

5521

16683

7864

"~ ~

Number on 

geologic 

section

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

USGS 

identifier

Mk-gl2

Mk-Wll

Mk-g9

R2

Mk-gl6

Nw-7

Nw-5

Nw-21

Nw-25

Nw-W3

Nw-29

Mt-32

Mt-3

Mt-16

Mt-N3

Mt-5

Mt-11

Mt-22

Mt-28

Os-6

Cl-13

Cl-10

C1-N5

Cl-18

Cl-20

Cl-17

Cl-3

Rc-9

Rc-2

Rc-g3

Rc-g64

Rc-g8

Rc-g7

Rc-gl7

R5

Section 

Township 

Range

13-11N-18W

16-11N-17W

03-11N-16W

30-12N-15W

13-12N-15W

01-12N-14W

10-12N-13W

11-12N-13W

13-12N-13W

16-12N-12W

33-13N-11W

05-13N-10W

03-13N-10W

26-14N-10W

04-14N-09W

23-15N-09W

17-15N-08W

12-16N-08W

12-16N-08W

34-17N-07W

22-17N-06W

06-17N-05W

21-18N-05W

12-18N-05W

06-18N-04W

36-20N-04W

19-20N-03W

29-21N-03W

20-21N-03W

23-22N-03W

06-22N-02W

21-24N-02W

02-24N-02W

36-23N-01W

12-25N-02W

Township name, county

Fruitland, Muskegon

Fruitland, Muskegon

Dalton, Muskegon

Holton, Muskegon

Holton, Muskegon

Bridgeton, Newaygo

Garfield, Newaygo

Garfield, Newaygo

Garfield, Newaygo

Brooks, Newaygo

Big Prairie, Newaygo

Aetna, Mecosta

Aetna, Mecosta

Mecosta, Mecosta

Austin, Mecosta

Colfax, Mecosta

Martiny, Mecosta

Chippewa, Mecosta

Chippewa, Mecosta

Orient, Osceola

Garfield, Clare

Surrey, Clare

Lincoln, Clare

Lincoln, Clare

Hatton, Clare

Frost, Clare

Franklin, Clare

Roscommon, Roscommon

Roscommon, Roscommon

Denton, Roscommon

Bachus, Roscommon

Higgins, Roscommon

Higgins, Roscommon

Richfield, Roscommon

South Branch, Crawford

Appendix A 27
Table A2. Identification of geophysical and geologic logs used in the construction of hydrogeologic section 

B-B' f Wexford County to Shiawassee County, Michigan

[Permit numbers are assigned to oil and gas wells by Michigan Department of Natural Resources; dashes indicate that no permit number 

was issued or that well was used for purposes other than oil or gas exploration or production. U.S. Geological Survey (USGS) identifiers 

are numbers assigned to logs on file at USGS, indicating county where well is located, type of well, and type of log]

Permit 

number

29755

10303

35866

12304

10661

18209

20742

10754

25007

15934

14591

11670

9039

8573

14639

32394

13739

12375

26256

12911

11747

18330

23980

15597

16275

16791

9464

10536

14844

13920

33991

33382

3703

33313

33321

3586

1198

23376

Number on 

geologic 

section

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

USGS 

identifier

Wx-g20

Wx-3

Wx-Nl

Wx-4

Wx-g58

Wx-6

Wx-5

Os-8

Os-gl5

Os-9

Os-24

Os-31

Os-1

Os-g97

Os-g65

Os-4

Os-Nl

Os-12

Os-29

Ib-g45

Ib-65

Ib-13

Ib-57

Ib-Ll

Ib-6

Ib-7

Ib-W2

Ib-10

Gr-g23

Gr-Wll

Gr-3

Gr-2

Gr-1

Gr-NFD-1

Gr-NFD-4

Gr-g79

Ct-N2

Ct-Nl

Ct-g21

Sw-g2

Sw-g9

Section 

Township 

Range

16-24N-11W

11-23N-11W

05-23N-10W

11-22N-10W

24-22N-10W

36-22N-10W

13-21N-10W

09-20N-09W

14-20N-09W

19-20N-08W

34-20N-09W

29-20N-08W

19-19N-08W

25-19N-08W

07-18N-07W

09-18N-07W

03-17N-07W

03-17N-07W

12-17N-07W

10-16N-06W

20-16N-06W

02-15N-06W

13-15N-06W

16-14N-05W

01-14N-05W

17-14N-04W

27-14N-04W

28-13N-04W

13-12N-04W

30-11N-02W

36-11N-03W

26-10N-03W

36-10N-03W

28-10N-02W

22-09N-02W

36-10N-01W

24-08N-02W

09-07N-01W

25-07N-01W

01-05N-01E

25-05N-02E

Township name, county

Hanover, Wexford

Antioch, Wexford

Colfax, Wexford

Selma, Wexford

Selma, Wexford

Selma, Wexford

Cherry Grove, Wexford

Sherman, Osceola

Sherman, Osceola

Highland, Osceola

Sherman, Osceola

Highland, Osceola

Hartwick, Osceola

Hartwick, Osceola

Sylvan, Osceola

Sylvan, Osceola

Orient, Osceola

Orient, Osceola

Orient, Osceola

Coldwater, Isabella

Coldwater, Isabella

Sherman, Isabella

Sherman, Isabella

Deerfield, Isabella

Deerfield, Isabella

Union, Isabella

Union, Isabella

Lincoln, Isabella

Seville, Gratiot

Emerson, Gratiot

Arcada, Gratiot

Newark, Gratiot

Newark, Gratiot

North Star, Gratiot

Washington, Gratiot

Hamilton, Gratiot

Greenbush, Clinton

Ovid, Clinton

Ovid, Clinton

Woodhull, Shiawassee

Perry, Shiawassee

28 Hydrogeologic Framework of Miaaisaippian Rocka 

in the Central Lower Peninsula of Michigan
86°

45'

44'

43'

85°

7

84° 83°

\ BOUNDARY OF RASA

Base from U.S. Geological Survey 1:500,000 

state base map, 1970 20

I

40 60 MILES

\ T I 

20 40 60 KILOMETERS

EXPLANATION

B B1 GEOLOGIC SECTION LINE

41 DATA POINT Number assigned for reference 

purposes only. For additional information 

see tables 1 and 2

Figure A1. Location of geophysical and geologic logs used in the construction of hydrogeologic 

sections A-A' and B-B', central Lower Peninsula of Michigan.

Appendix A 29
? if

3 ^

S 2.

5" a*

3 3

30 MILES 

I

10 20

\ 

30 KILOMETERS

VERTICAL SCALE IS EXAGGERATED 

DATUM IS SEA LEVEL

EXPLANATION

GEOLOGIC CONTACT Dashed where

approximately located 

LOCATION OF LOGGED BOREHOLE Refer

to Appendix 1, table 1, column 2

FORMATION

HDHfTl

I PS I 

I Pcu I

I Mbp I 

I Mm I 

I Mn I 

I Mim I 

I Mcu I 

r"Mc"1

Drift Glacial deposits (undifferentiat

"Red Beds"

Grand River Saginaw Formations

(undifferentiated)

Sagina-yr Formation (principally shale) 

Parma Sandstone 

Bayport Limestone 

Michigan Formation

Marshall Sandstone (Napoleon membe

Marshall Sandstone (lower Marshall u

Marshall Sandstone (confining unit li

Coldwater Shale

Figure A2. Generalized hydrogeologic section A-A' showing stratigraphic relations of Mississippian and younger geolog

to Crawford County, Michigan. (Line of section shown in fig. A1.)
B

t

1

11

B 91012 13 17 IB 19

24

25 2827

I I I

30 31 32 3

II I 

10

I

20

I

30 MILES

~ 

10 20

I 

30 KILOMETERS

GEOLOGIC CONTACT Dashed where

approximately located 

LOCATION OF LOGGED BOREHOLE Refer

to Appendix 1, table 2, column 2

VERTICAL SCALE IS EXAGGERATED 

DATUM IS SEA LEVEL

EXPLANATION

FORMATION

("Drift"! Drift Glacial deposits (undifferentiat

r~JF~1 "Red Beds"

I Pa I Grand River-Saginaw Formations

	(undifferentiated)

I PCU l Saginaw Formation (principally shale)

I P»P ) Parma Sandstone

I MbP I Bayport Limestone

I Mm I Michigan Formation

I Mn ] Marshall Sandstone (Napoleon membe

I Mim ) Marshall Sandstone (lower Marshall u

I Mcu | Marshall Sandstone (confining unit lit

I Me I Coldwater Shale

2 Figure A3. Generalized hydrogeologic section B-B' showing stratigraphic relations of Mississippian and younger geolog

to Shiawassee County, Michigan. (Line of section shown in fig. A1.)

APPENDIX B. INTERPRETATION OF GEOPHYSICAL AND GEOLOGIC 

LOGS

CONTENTS

Geophysical logs ................................................... 35

Geologic logs ..................................................... 35

Figure Bl. Sample suite of geophysical logs showing typical electric-log, gamma-ray log, 

and porosity-log traces of selected Mississippian rock units in the 

central Lower Peninsula of Michigan ............................... 36

Appendix B 33

GEOPHYSICAL LOGS

Production of oil and gas in the Michigan Basin began in 1925 (Dorr and Eschman, 1970, p. 237), and 

Michigan continues to be a major producer of hydrocarbons. Geophysical logging of hydrocarbon-exploration 

boreholes became common practice in the 1940' s. RASA investigators located approximately 300 electricalresistivity/spontaneous-potential logs (or old electric logs; Hilchie, 1979) of boreholes drilled before 1953, 

which were run in shallow-cased boreholes that were open to Pennsylvanian and Mississippian rocks. At many 

places, the logged boreholes were open to Pleistocene glacial deposits, which allows for characterization of 

geophysical properties of all units in the aquifer system. Discoveries of natural gas in Mississippian sandstones in the late 1950's resulted in continued exploration activity; most boreholes drilled after 1960 have been 

logged with a suite of improved geophysical-logging tools, including caliper, gamma-ray, dual-induction or 

dual-laterolog, neutron-porosity, and density-porosity equipment. Westjohn (1989, 1994b) included detailed discussion of applications of geophysical logs in the characterization of hydrostratigraphic units in the Michigan 

Basin regional aquifer system study area. Aquifers and confining units have distinct geophysical-log traces, as 

can be seen in figure Bl.

Permeable lithologies can be identified from traces on electrical-resistivity-log, due in part to the common 

use of high-density muds (densities greater than 9 grams per cubic centimeter) during drilling of oil and gas 

wells. Filtrate from heavy drilling mud typically displaces native pore fluid in permeable formations. The 

effects of infiltration of fluids from drilling mud can be measured with electrical-resistivity-logging tools. A 

common design of logging tools involves multiple electrode configurations that allow measurement of electrical 

resistivity at three lateral distances from the borehole opening. One configuration of electrodes is designed to 

measure electrical resistivity very near the borehole, in the flushed zone (area of total displacement of formation 

fluid by mud filtrate; Hearst and Nelson, 1985, p. 28-30). A second configuration measures electrical resistivity in the transition zone (area of mixing of formation fluid and mud filtrate), and a third configuration measures 

electrical resistivity in the noninvaded zone (true formation resistivity). In boreholes where formation fluid and 

mud filtrate have substantially different electrical resistivities (which is the general case in Michigan) and 

drilling fluid has invaded permeable strata, a separation of electrical-resistivity-log traces is observed. The separations of electrical-resistivity-log traces commonly observed in aquifers of the study area are illustrated by the 

example log (fig. Bl). The amount of separation of the three traces recorded on electrical-resistivity logs is a 

function of formation permeability and the distance that fluid has infiltrated the formation, as well as the amount 

of contrast in electrical resistivity between formation fluid and mud filtrate.

Electric logs and combination geophysical-log suites (gamma ray, neutron porosity, density porosity, and 

dual resistivity) are available for much of the study area from the Oil and Gas Division, Michigan Geological 

Survey. Geophysical logs are numerous for some areas of the basin where discovery wells or indications of oil 

and gas stimulated exploration activities. Exploration boreholes in areas surrounding oil- and gas-discovery 

wells also were commonly logged.

Geophysical logs are sparse or nonexistent for most of the Thumb Area (fig. 1) and the southern part of 

the study area, with the exception of a few gamma-ray logs that were run in cased boreholes.

GEOLOGIC LOGS

Geologic logs of oil, gas, and water wells are on file with the Michigan Geological Survey and the 

Michigan Department of Public Health. Geologic descriptions recorded on logs of oil, gas, and water wells 

(lithologic data, formation tops, and so forth) were used to map aquifer- and confining-unit boundaries in parts 

of the study area for which geophysical logs are sparse or unavailable.

Appendix B 35
o 

o o

.- CM 10 * "« 

30VJMHS QNV1M0138 133JNl'Hld3Q 

36 Hydrogeologic Framework ofMississippian Rocks in the Central Lower Peninsula ofMichigan

mma ray log Hydrogeologic Bulk density and Water-quality and 

(API units) unit formation density Re«l«tlvlty log resistivity data for 

log* (percent) (ohm-meter«) given depth

Bulk density 

2.0 o.O

150 45 Porosity Q _ lg Q2 2QQQ

[

[

a

 *- 

ig

<

 ^

<:

^

1

1 1 n

n 1 1

2*

}

^

 \

i

7

i==*-

 ^

S^H.

INI

Saglnaw 

aquifer

Saglnaw 

confining 

unit

Parma Bayport 

aquifer

Michigan 

confining 

unit

Marshall 

aquifer

11 If-,

-c

«--:

n rr

>"£'

1*.

J

%

>

-£

vV r

> X

: s

V)

O

i n i

j

v

H+l-f

Tur

^ ii i

nun

mil

i mm

s

~b~

£

%

VCL

>

f

IIMI

vinin

^

t :

t :

1

:~~y

^

i

p

i

j

> 

r-v^- 

f

L

Tlinii

i mm 

]'

i tun

140 feet: dls*olvedsollds concentration, 

244 mg/L (milligrams 

209-268 feet: dlssolve

sollds concentration. 

27.500 mg/L

378-402 feet: dlssolve

sollds concentration. 

98.000 mg/L; resistivit

4-5 0-m (ohm-meter

^496 feet: dlssolvedsollds concentration, 

99.000 mg/L; resistivit

3-4 n-m

Figure B1. Sample suite of geophysical logs showing typical electric-log, gamma-ray-log, and porosity-log traces of s

units in the central Lower Peninsula of Michigan.
APPENDIX C. LOCATIONS OF BOREHOLES AND LOGS

CONTENTS

Figures Cl. Locations of boreholes and logs used to construct surface-configuration and

thickness maps of Michigan confining unit, central Lower Peninsula of Michigan . . 39

C2. Locations of boreholes and logs used to construct surface-configuration map

of the Marshall aquifer, central Lower Peninsula of Michigan ............... 40

C3. Locations of boreholes and geophysical logs used to construct thickness map of

Marshall aquifer, central Lower Peninsula of Michigan ................... 41

C4. Locations of boreholes and logs used to construct surface-configuration map

of Coldwater confining unit, central Lower Peninsula of Michigan ............ 42

App.ndixC 37

86*

45'

44°

43*

42'

85' 84* 83'

BOUNDARY OF RASA 

STUDY AREA

SUBCROP OF 

PENNSYLVANIAN ROCKS

ERIE

Base from U.S. Geological Survey 1:500.000 

state baso map, 1970 20

I

40 60 MILES

1 I 

0 20 40 60 KILOMETERS

EXPLANATION

 DATA POINT Shows location of boreholes and 

logs used to construct figure 4 and 5

Figure C1. Locations of boreholes and logs used to construct surface-configuration and thickness 

maps of Michigan confining unit, central Lower Peninsula of Michigan.

Appendix C 39
86° 85° 84° 83'

45° -

44" -

43" -

42'

f'

\

(p/ BOUNDARY OF RASA 

STUDY AREA

I

s

SUBCROP OF 

MICHIGAN FORMATION

Base from U.S. Geological Survey 1:500,000 

state base map, 1970 20 

I

40

I

60 MILES

0 20

I I 

40 60 KILOMETERS

EXPLANATION

DATA POINT Shows location of boreholes and 

logs used to construct figure 6 and 7

Figure C2. Locations of boreholes and logs used to construct surface-configuration map of Marshall 

aquifer, central Lower Peninsula of Michigan.

40 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula off Michigan
86° 85* 84* 83*

45°

44'

43*

42°

s

(?;/ BOUNDARY OF RASA 

STUDY AREA

/ SUBCROP OF 

/ MICHIGAN FORMATION

LAKE 

ERIE

Base from U.S. Geological Survey 1:500,000 

state base mop, 1970 20

I

40 60 MILES 

I______I

20

\ I 

40 60 KILOMETERS

EXPLANATION

DATA POINT Shows location of boreholes and type 

of log interpreted in construction of figure 7

e Resistivity log 

+ Gamma ray log

Figure C3. Locations of boreholes and geophysical logs used to construct thickness map of Marshall 

aquifer, central Lower Peninsula of Michigan.

Appendix C 41
86° 85* 84° 83*

45'

44° 

43° 

42°

SUBCROP OF 

COLDWATER SHALE

s

BOUNDARY OF RASA 

STUDY AREA

L A K E 

ERIE

Base from U.S. Geological Survey 1:500,000 

state base map, 1970 20

I

40 60 MILES 

J______I

T I 

20 40 60 KILOMETERS

EXPLANATION

 DATA POINT Shows location of boreholes and 

logs used to construct figure 8

Figure C4. Locations of boreholes and logs used to construct surface-configuration map of Coldwater 

confining unit, central Lower Peninsula of Michigan.

42 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan
APPENDIX D. HYDRAULIC PROPERTIES OF MISSISSIPPIAN 

SANDSTONES

CONTENTS

Table Dl. Range of porosities and vertical hydraulic conductivities measured of

43 Mississippian sandstone core specimens ........................... 45

Table D2. Range of porosities and horizontal hydraulic conductivities measured of

20 Mississippian sandstone core specimens ........................... 45

Figure Dl. Porosities and vertical hydraulic conductivities measured of Mississippian

sandstone core specimens from the central Lower Peninsula of Michigan ........ 46

Figure D2. Porosities and horizontal hydraulic conductivities measured of Mississippian

sandstone core specimens from the central Lower Peninsula of Michigan ........ 46

Appendix D 43

Table D1. Range of porosities and vertical hydraulic conductivities measured of 43 Mississippian sandstone 

core specimens

[Sandstone cores are from the lower Marshall sandstone or Napoleon Sandstone (member of Marshall Sandstone); these unite form the 

Marshall aquifer. Micaceous sandstones/siltstones form part of the Marshall sedimentary sequence, and because of low hydraulic 

conductivities, are not included in thickness map of the Marshall aquifer. See fig. Dl, a plot of all porosity and vertical-hydraulicconductivity data. Abbreviations: Kv, vertical hydraulic conductivity; ft/d, feet per day]

Sample type Porosity range Kv (ft/d) Kv (ft/d) 

(no. of (percent) (minimum) (maximum) 

samples)

Sandstone 16-25 3.4 X KT4 1.3 X 10°

(28)

Micaceous 15-23 8.5 X KT6 6.0 X 10'3

sandstone/

siltstone

(15)

Table D2. Range of porosities and horizontal hydraulic conductivities measured of 20 Mississippian sandstone 

core specimens

[Sandstone core samples are from the lower Marshall sandstone or Napoleon Sandstone (member of the Marshall Sandstone); these unite 

form the Marshall aquifer. Micaceous sandstones/siltstones form the basal part of the Marshall sedimentary sequence, and because of low 

hydraulic conductivities, are not included in thickness map of the Marshall aquifer. See fig. D2, a plot of all porosity and horizontalhydraulic-conductivity data. Abbreviations: Kh, horizontal hydraulic conductivity; ft/d, feet per day]

Sample type

(no. of

samples)

Sandstone

(10)

Micaceous

sandstone/

siltstone

(10)

Porosity range Kv (ft/d)

(percent) (minimum)

17-25 7.0 X 10'3

11-21 8.9 X 10-6

Kv (ft/d)

(maximum)

1.8 x 10°

2.5 x lO'3

Appendix D 45
£.OX IU g"

p

o

g< 2.8x10-2

o

a:

O LJ

^

a£ 

£ 2 2.8x10~4

_i

o

i 

cc

LU

2.8x1 0~6

W W E s°\ s** -

1 ^ K ^ ]

r K * K i

 Vstef ^C -

.^n" X X

O n

r o n i

D w n 

r w D i

D D :

on J

: :

D -

'l 1 1 1 I 1 1 , 1 1 1 1 1 1 I I 1 1 I 1 I 1 I 1 1 ! 1 1 1 1 I I 1 1 1 I 1 1 I 1 ! 1 1 1 ! 1 1 1 1 1 1 1 1 1 I 1 1 1 1

EXPLANATION

h10-4 ^§ a MICACEOUS SANDSTONE/

o o SILTSTONE

10 -5 z^ X SANDSTONE

O iii

a. o

10 -6 D^

io-7 lg

z

TO"8 °. z

a: 

LJ

1 0 ^

14 16 18 20 22 24 26

POROSITY, IN PERCENT

Figure D1. Porosities and vertical hydraulic conductivities measured of Mississippian sandstone core

specimens from the central Lower Peninsula of Michigan.

^ 2.8x10° in ~3

P 

o

Q

ol 2.8x10-2

OQ:

^o!

<

jjjjtj

^ z 2.8x10 ~4 

<i 

z

0

£

o

I fi

 > Q., 1 r\ o

X x« :

X Xi

^ :

x :

X n =

& ~

!

1=3 D : 

0° 1

D

n a \

1 , , I I I . . , 1 . , , , , , , , , 1 , , , I I , I . I

t EXPLANATION

ID"4 5z D MICACEOUS SANDSTONE/

g 8 SILTSTONE

10 _5 o^ X SANDSTONE

o§

in _6 ^ to i u ^ Q:

CC LJ Q h-

>-LJ

10-7 ^|

Z °

10-8 O z

QT

o

m -9 Z

10 15 20

POROSITY, IN PERCENT

25

Figure D2. Porosities and horizontal hydraulic conductivities measured of Mississippian sandstone core 

specimens from the central Lower Peninsula of Michigan.

46 Hydrogeologic Framework of Mississippian Rocks 

in the Central Lower Peninsula of Michigan