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STATE OF ILLINOIS
DEPARTMENT OF REGISTRATION AND EDUCATION
The Middle Devonian Strata
of Southern Illinois
William G. North
CIRCULAR 441 1969
ILLINOIS STATE GEOLOGICAL SURVEY
URBANA, ILLINOIS 61801
John C. Frye, Chief
CONTENTS
Page
ABSTRACT 1
INTRODUCTION 2
Previous Work 2
Methods of Study 4
Acknowledgments 4
GEOLOGIC SETTING 5
Sparta Shelf 5
Wittenberg Trough 5
Sangamon Arch 5
Vandalia Arch 5
STRATIGRAPHY 7
Classification 7
Correlation 9
GRAND TOWER LIMESTONE 10
Thickness and distribution 10
Lithology 14
Geophysical characteristics 14
LINGLE FORMATION .'14
Howardton Limestone Member 2 2
Thickness and distribution 22
Lithology 24
Geophysical characteristics 24
Stratigraphic relations 24
Tripp Limestone Member 25
Thickness and distribution 25
Lithology 27
Geophysical characteristics 28
Stratigraphic relations 2 8
Misenheimer Shale Member 28
Thickness and distribution 29
Lithology 29
Stratigraphic relations 29
Walnut Grove Limestone Member 29
Thickness and distribution 30
Lithology 3 0
Rendleman Oolite Bed 30
ALTO FORMATION 31
BLOCHER SHALE 32
Thickness and distribution 3 2
Lithology 3 2
Geophysical characteristics 3 2
Stratigraphic relations 34
SWEETLAND CREEK SHALE 34
Thickness and distribution 34
Lithology 34
Geophysical characteristics 34
Stratigraphic relations 3 6
GEOLOGIC HISTORY 38
REFERENCES 39
APPENDIX A - Wells Used in Compiling Cross Sections ... 41
APPENDIX B - Geologic Sections 42
THE MIDDLE DEVONIAN STRATA
OF SOUTHERN ILLINOIS
William G. North
ABSTRACT
The Middle Devonian rocks have long been a major
source of oil in the Illinois Basin. These rocks are ex-
posed in southern Illinois in a small area along the Mis-
sissippi Valley in the extreme southwestern part of the
state. In the outcrop area they have a strikingly different
composition from equivalent strata in the deep part of the
basin. Except for a thin basal transgressive sandstone ,
the outcropping section consists largely of shallow-water
carbonates that are exceptionally pure at the base and be-
come shaly upward. The pure carbonates (Grand Tower
Limestone) are extensive throughout the basin, whereas the
overlying shaliercarbonates and interbedded shale (Lingle
and Alto Formations) appear to grade eastward into shale
only a few miles east of the outcrop area. The shale is
divided into black shale (Blocher Shale) below and gray
shale (Sweetland Creek Shale) above.
Facies and thickness variations are related to shal-
lowing of the water over positive areas, the Sparta Shelf on
the west and the Sangamon and Vandalia Arches on the
north, the sinking Wittenburg Trough on the south side of
the Sparta Shelf, and the deeper water of the Illinois Basin
east of the DuQuoin Monocline.
The Lingle Limestone is subdivided into four mem-
bers, the Howardton Limestone Member at the base, the
Tripp Limestone Member, the Misenheimer Shale Member,
and the Walnut Grove Limestone Member. All except the
Misenheimer are new. A widespread oolite bed in the Wal-
nut Grove, named the Rendleman Oolite Bed, is also new.
These units, with distinctive geophysical key beds in the
Sweetland Creek Shale, permit detailed tracing of Middle
Devonian strata across the Illinois Basin.
1
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
INTRODUCTION
The Middle Devonian rocks of southern Illinois have been productive of
large quantities of oil. They contain both reservoirs and source rocks, and a
knowledge of their complex lateral variations is important in the search for new
production, in the study of methods for secondary and tertiary production from
partially depleted fields, and in the use of the reservoirs for storage of natural
gas. Extensive drilling in the Illinois Basin has provided a large amount of geo-
physical data and many well samples and has made it both possible and timely to
gain a greater understanding of Middle Devonian stratigraphy.
The Middle Devonian strata of southern Illinois, in general, are shallow-
water carbonates in the lower part and shale in the upper part. They range in thick-
ness from nothing at the west to about 400 feet in the deep part of the Illinois
Basin. The lowermost unit within this section, the Grand Tower Limestone, is con-
sidered in more detail by Meents and Swann (1965). The younger formations, given
more detailed consideration in this report, are the Lingle Formation, Alto Formation,
Blocher Shale, and Sweetland Creek Shale.
The purposes of the investigation are to determine the thickness and distri-
bution of the formations at and beneath the Middle-Upper Devonian boundary of
southern Illinois and to study the lithologic changes both vertically (stratigraphic)
and laterally (facies) within and between the formations. Of particular importance
are the relations between the lower units of the New Albany Shale Group and the
upper units of the Middle Devonian carbonate sequence.
The study is limited to the Middle and Upper Devonian strata of east-cen-
tral and southern Illinois (fig. 1). The significant relations of the shale versus
limestone facies are located south of the Vandalia Arch. Moreover, the carbonates
to the north of the arch contain little or no silt and clay, and, therefore, their in-
terpretation requires a different approach that is beyond the scope of this study.
Previous Work
The outcrop area of Devonian formations in southwestern Illinois and south-
eastern Missouri has been intensively studied. Investigations encompassing the
entire Devonian section include those of Keyes (1894) and Croneis (1944) in south-
eastern Missouri and Savage (192 0a, 19 20b) and Weller (1944) in southwestern
Illinois. Savage (1920a, 1920b) lists many fossils. Orr (1964) describes the type
Lingle Formation and type Alto Formation sections and their conodont faunas. Grim-
mer (1968) describes the megafauna of the shale in the Lingle Formation.
Regional correlations are discussed by Savage (1910, 1920a, 1920b, 1925),
Cooper et al. (1942), Cooper (1944), Weller (1944), and Collinson et al. (1967).
The report by Collinson et al. is the most inclusive as well as most recent.
The subsurface Devonian stratigraphy of southern Illinois is summarized by
Workman (1944). Workman and Gillette (1956) studied the New Albany Shale through-
out its extent in Illinois. Warthin and Cooper (1944) discuss Middle Devonian for-
mations. All of these reports are based primarily on sample studies. Several re-
cent studies use geophysical logs in conjunction with samples and/or conodont
data. Schwalb (1955) describes the Geneva Dolomite. Whiting and Stevenson (196 5)
delineate the Sangamon Arch of west-central Illinois and describe the Middle De-
vonian stratigraphic relations around the arch. Meents and Swann (1965) describe
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
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4 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
the Grand Tower Limestone of southern Illinois. Collinson et al. (1967) summarize
knowledge of Devonian stratigraphy throughout the north-central states using geo-
physical and sample data in the subsurface. James (1965) studied the Sweetland
Creek Shale of western Illinois using samples and conodonts.
Methods of Study
In this study most of the outcrops of southwestern Illinois were examined.
Geologic sections that contain type sections of new units are given in Appendix B.
The available chip samples from wells in the outcrop area and selected chip samples
from wells elsewhere in southern Illinois were studied. Except where more than
one well record is available within a section, every available geophysical log,
core description, and sample description was examined (fig. 1). Forty of the wells
were used in the cross sections (fig. 2).
The list of wells used in compiling the
cross sections is given in Appendix A.
Between drill holes in the cross
sections, formation and member con-
tacts at facie s boundaries are shown by
vertical lines — "vertical cutoff. " Sloping
lines between drill holes indicate thick-
ening or thinning without evidence of
facies relation.
Distinctive, readily traceable,
features or positions on geophysical
logs are called "key beds" in this re-
port.
Acknowledgments
The writer wishes to express his
deep gratitude to the late David H.
Swann of the Illinois State Geological
Survey, who suggested the topic and
gave much help in solution of the prob-
lems. This report is based on a doctor-
ate thesis at the University of Illinois.
Ralph L. Langenheim, Jr., thesis advi-
sor, gave constructive criticism in all
phases of the study. Albert Carozzi,
Carleton A. Chapman, C. John Mann,
and R. D. Seif, of the University of
Illinois, and Elwood Atherton, Charles
W. Collinson, Wayne F. Meents, and
H. B. Willman, of the Illinois State Ge-
ological Survey, critically read the man-
uscript and gave many helpful sugges-
tions.
Fig. 2 - Lines of cross sections.
Wells listed in Appendix A.
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 5
GEOLOGIC SETTING
The complex facie s and distribution patterns of Middle Devonian sediments
were influenced by two positive features that must not have been very far above
Middle Devonian sea levels — the Sangamon Arch in central Illinois and the Sparta
Shelf in southwestern Illinois (fig. 3). A northeastward extension of the Sparta
Shelf into easternmost Illinois, inferred from thinning of Middle and lower Upper
Devonian units, is called the Vandalia Arch. In the southeast, the Moorman Syn-
cline represents the area of maximum subsidence. In the southwest, the Sparta
Shelf was truncated by the Wittenberg Trough, a narrow, elongate structure, which
was persistently negative during Middle and Late Devonian time.
Sparta Shelf
The broad wedge-shaped area in southwestern Illinois where Middle Devon-
ian strata are absent (fig. 3) was recognized as a spur of the Ozark Uplift by Work-
man and Gillette (1956) and was formally named the Sparta Shelf by Meents and
Swann (1965). The shelf is bounded on the east by the eastern slope of the DuQuoin
Monocline and on the south by the Wittenberg Trough. It gradually merges north-
ward into the depositional basin. The DuQuoin Monocline extends southward sev-
eral miles beyond the eastern end of the Wittenberg Trough, thus effectively sepa-
rating the trough from the deeper portion of the Illinois Basin to the east.
Wittenberg Trough
The Wittenberg Trough (Meents and Swann, 1965) is partially preserved in
isolated fault blocks along the Ste. Genevieve -Rattlesnake Ferry Fault that ex-
tends more than 70 miles from Ste. Genevieve County, Missouri, to Union County,
Illinois (fig. 3) .
The Wittenberg Trough has had a long and complex history. It first sub-
sided late in early Devonian time, which resulted in preservation within the struc-
ture of Lower Devonian strata that in areas adjacent to the trough were truncated
prior to Middle Devonian time. Deposition continued through Middle Devonian
and into Late Devonian. The trough was greatly deformed by post-Mis sis sippian
deformation (Meents and Swann, 1965). At the eastern end of the fault in northern
Union County, the axis of the depositional trough turns southward, which indicates
that the southern extremity of the DuQuoin Monocline formed a barrier between the
trough and the deep part of the Illinois Basin to the east.
Sangamon Arch
The Sangamon Arch (Whiting and Stevenson, 1965) is a low, broad, northeast-
southwest trending structure that extends from east-central Missouri into east-cen-
tral Illinois (fig. 3). The structure was a positive area during the Middle Devonian.
Vandalia Arch
Workman and Gillette (1956) defined the Vandalia Arch on the basis of
stratigraphic relationships of Mississippian strata, but the arch influenced the
thickness and facies of certain Middle Devonian units. The arch trends northeast-
southwest, parallel to and approximately 50 miles south of the Sangamon Arch. To
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
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sippian and Upper Devonian.
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
the west, the Vandalia Arch merges with the Sparta Shelf in the Clinton County
area (T. 2 and 3N., R. 1 W.); it extends eastward to the Indiana line in Edgar
County (about T. 12 N.).
STRATIGRAPHY
Classification
The Middle and Upper Devonian strata of southern Illinois are dominated
by carbonates in the lower part and argillaceous rocks in the upper part. The
carbonates are the uppermost part of the Hunton Limestone Megagroup (Swann and
Willman, 1961), which contains strata as old as lowermost Silurian. Shale of the
upper part belongs to the lowermost part of the New Albany Shale Group, the low-
est unit within the Knobs Shale Megagroup, which includes Upper Devonian and
Mississippian (Kinderhookian and Valmeyeran) strata.
The carbonate units are the Grand Tower Limestone (below), the Lingle
Formation, and the Alto Formation (fig. 4). The Grand Tower Limestone, originally
defined by Keyes (1894), includes relatively pure carbonate strata between the
base of the Dutch Creek Sandstone Member and the first occurrence of argillaceous
limestone. The Grand Tower Limestone overlies the major pre-Middle Devonian
erosion surface, the sub-Kaskaskia unconformity (Sloss, 1963). The first occur-
rence of argillaceous limestone in southwestern Illinois corresponds with the first
occurrence of fossils correlative with the Hamilton Group fauna of New York
(Meents and Swann, 1965) and the zone of abundant Microcyclus, a button-shaped
solitary coral. The Grand Tower Limestone occurs south of the Sangamon Arch.
In the southwestern Illinois outcrop area, the Grand Tower Limestone is
overlain by shaly limestone and calcareous shale that is very poorly exposed. In
the southern part of the outcrop area, Savage (1920a) referred these rocks to a
lower shale unit (Misenheimer Shale) and an upper limestone unit (Lingle Limestone).
He thought that the shale pinched out northward so that the Lingle Limestone rested
directly on the Grand Tower Limestone at the Grand Tower type locality in the north-
ernmost part of the outcrop area. Weller (1944), however, considered the shale to
be too poorly defined to differentiate and included it within the Lingle Limestone
Formation. This was followed by Orr (1964) and Meents and Swann (1965).
Cooper et al. (1942) and Cooper (1944) distinguished the Misenheimer Shale from
the Lingle Limestone in the Lingle type area on the basis of megafossils but con-
sidered the fossils of the Lingle Limestone at the Grand Tower type locality to be
older than those of the Misenheimer Shale. For this reason, Grimmer (196 8) traced
the Misenheimer Shale from the southernmost outcrop area to the northern outcrop
area. He tentatively assigned the Missouri term St. Laurent Limestone to the low-
er limestone, the Misenheimer Shale Member of the Lingle Limestone to the middle
shale, and the Lingle Limestone to the upper limestone.
The name Lingle Formation has been long accepted for the limestone over-
lying the Grand Tower Limestone and overlain by the Sweetland Creek Shale or Alto
Formation, and its use is continued here. The term St. Laurent Limestone in Illinois
is rejected because as used in its type area in Missouri, it includes the Alto For-
mation (Dake, 1918; Weller and St. Clair, 1928; Collinson et al., 1967). The term
Misenheimer Shale is retained as a member of the Lingle Formation. Three new
members of the Lingle Formation are named in this report (fig. 4). The Howardton
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
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MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 9
Limestone Member (at the base) is overlain by the Tripp Limestone Member. The
Walnut Grove Limestone Member (at the top) overlies the Misenheimer Shale Member.
An oolite bed within the Walnut Grove Limestone in the outcrop area is here named
the Rendleman Oolite Bed (fig. 4).
The Alto Formation consists of strata overlying the limestone of the Lingle
Formation and underlying the shale of the New Albany Group, as originally defined
by Savage (1920a). The formation, however, is restricted to the southwestern
Illinois outcrop area and is not extended into the southern Illinois subsurface, as
Workman (1944) and Meents and Swann (1965) suggested.
Two lower formations of the -New Albany Shale Group are included in this
study— the Blocher Shale and the Sweetland Creek Shale. The Blocher Shale is the
carbon-rich black shale that is the lowermost unit in the type area of the New Al-
bany Shale Group in Indiana (Campbell, 1946; Lineback, 1968; Collinson et al.,
1967). Because this report, as well as that of Collinson et al., is based on electric
log studies, it disagrees in some respects with that of Lineback, who picked the top
of the Blocher Shale in southern Indiana on the basis of well cuttings and placed
the boundary somewhat higher stratigraphically. The Blocher Shale is present only
in the southeastern part of the area of this study, and apparently is in facies re-
lationship with the Tripp Limestone Member of the Lingle Formation to the west
(fig. 4).
The Sweetland Creek Shale rests on the Blocher Shale to the east and the
carbonates of the Lingle Formation to the west. The Sweetland Creek Shale was
named by Udden (1899) for exposures in southeastern Iowa, and the term was used
in western Illinois for many years. Workman and Gillette (1956) discontinued the
use of the term Sweetland Creek in Illinois. In southern Illinois, Meents and
Swann (1965) differentiated a dominantly gray shale unit from the overlying black
shale in the New Albany Group and referred to it as the "unnamed shale. " James
(1965) and Collinson et al. (1967) reinstated the term Sweetland Creek and ex-
tended it to include the "unnamed shale" in southwestern Illinois. The Sweetland
Creek is a facies of both the overlying Grassy Creek Shale and underlying Lingle
Formation and is continuous from southeastern Iowa to southernmost Illinois.
Correlation
The correlation of the Devonian strata of the outcrop areas of southwestern
Illinois with adjacent states, New York, and Europe is shown by Collinson et al.
(1967), who give the ranges of both megafossils and microfossils. Conodont
faunas from some of the southwestern Illinois Middle Devonian sections are de-
scribed by Orr (1964). Megafossils are listed by Savage (1920a, 1920b) and
Grimmer (1968).
Both the megafossil and microfossil evidence indicates that the Grand Tower
Limestone correlates with parts of the Onondaga Group of New York and that the
Lingle Formation correlates with the Hamilton Group of New York. Only the older
portion of the Lingle Formation is present in the southern Illinois subsurface.
Approximately the upper half of the outcropping Lingle Formation grades into the
Blocher Shale and the Sweetland Creek Shale (fig. 4).
Conodonts in the Alto Formation of southwestern Illinois are considered by
Collinson et al. (1967) to be latest Middle Devonian in age.
10 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
GRAND TOWER LIMESTONE
The Grand Tower Limestone is the oldest Middle Devonian formation of
southern Illinois. Resting on the pre -Middle Devonian erosion surface, the forma-
tion is largely pure limestone and dolomite, although at almost all localities the
basal parts contain isolated sand grains or lenses of sandstone called the Dutch
Creek Sandstone Member. The Grand Tower Limestone consists mainly of fossili-
ferous limestone south of the Vandalia Arch, dolomite on the arch, and lithographic
limestone north of the arch.
The type section of the Grand Tower Limestone (fig. 5), as designated by
Keyes (1894) and illustrated by Meents and Swann (1965, p. 5, fig. 2), is in the
Devil's Bake Oven, Sec. 23, T. 10 S., R. 4 W., Altenburg Quadrangle, Jackson
County, Illinois. In the type section the formation is 157 feet thick. The lower
52 feet consists of sandstone at the base overlain by medium- to coarse-grained,
cross -bedded, light -colored, crinoidal limestone, the lower part of which is sandy.
The upper 105 feet consists of medium -grained, darker colored, crinoidal limestone
as well as fossiliferous, fine-grained to lithographic, dark -colored limestone.
The type section of the Grand Tower Limestone is atypical. A few miles to
the south and east of the type section the Grand Tower is only two-thirds as thick
and is similar to the lower 52 feet at the type section. The lithologies in the upper
105 feet of strata at the Bake Oven appear restricted to the western portion of the
Wittenberg Trough. On the basis of macrofossil evidence, Cooper (personal com-
munication) suggested that rocks equivalent to the upper dark limestone at Devil' s
Bake Oven do not crop out south of the Bake Oven.
In southernmost Illinois, the Grand Tower Limestone can be traced from the
outcrop to the subsurface with little hesitation (figs. 6 and 7). Farther north, how-
ever, correlation becomes difficult where the overlying Howardton Member of the
Lingle Formation loses a significant part of its argillaceous content and where the
Grand Tower changes from limestone to dolomite (fig. 5). Correlation there is aid-
ed by the occurrence of the Tioga Bentonite Bed, 10 to 30 feet below the top of the
Grand Tower Limestone (Meents and Swann, 1965). The Tioga Bentonite is less
than 1-foot thick and is readily recognized in geophysical logs throughout a large
area in eastern Illinois (fig. 3).
Thickness and distribution
In the outcrop region, the Grand Tower Limestone is thickest at the type
section (157 feet). Eastward, it thins abruptly to less than 50 feet over the south-
ern extension of the DuQuoin Monocline (fig. 5). Southward, the formation thins
toward its shoreline in T. 16 S., Pulaski County, Illinois.
In subsurface the Grand Tower Limestone ranges in thickness from 0 along
the flanks of the Sparta Shelf to greater than 250 feet in the Moorman Syncline of
southeastern Illinois (fig. 5). Stratigraphic relations indicate that the distribution
of the limestone has been changed little by subsequent erosion. Therefore, figure 5
shows essentially the primary depositional extent of the unit.
The distribution reported here is not significantly different from that shown
by Meents and Swann (1965, fig. 3), except in Jefferson, Perry, and Washington
Counties along the eastern side of the Sparta Shelf. In those counties they show
a thick tongue of Grand Tower extending westward onto the Sparta Shelf for 30 miles.
The greater part of these strata is referred herein to the Lower Devonian Backbone
Limestone, thus restricting the Grand Tower Limestone to east of the Sparta Shelf.
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
11
Fig. 5 - Thickness of Grand Tower Limestone
12
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
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14 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
This interpretation is based on (1) the absence of sand at the base of the tongue,
(2) tracing key beds within both the Lower Devonian and the Middle Devonian,
(3) lithologic similarity of the limestone with that of the Backbone Limestone, and
(4) the occurrence in a core in the lower part of the tongue of two Lower Devonian
guide fossils, Eodevonaria and Acrospirifer murchisoni.
The Grand Tower Limestone has the Dutch Creek Sandstone Member or
sandy limestone at its base over almost its entire extent; very few exceptions occur,
Meents and Swann (1965) showed a small sand-free area east of the Sparta Shelf,
but subsequent study has shown the sand to be there.
Lithology
The Grand Tower Limestone is uniformly fossiliferous, light colored, and
nearly pure carbonate. Except for the basal Dutch Creek Sandstone Member, in-
soluble residue characteristically amounts to less than 5 percent and consists of
angular to subrounded quartz grains ranging in size from coarse silt to coarse
sand. Limestone textures range from lithographic through coarse grained to micro-
breccia.
In the dolomitic area over the Vandalia Arch, the formation consists of dark,
sandy, crystalline dolomite (the Geneva Dolomite Member) at the base and lighter
colored, laminated dolomites above (Schwalb, 1955; Meents and Swann, 1965).
Only the latter are in contact with the overlying Lingle Formation. The laminated
dolomites are gray, yellow to tan, fine-grained dolomite. Insoluble content in
these strata is identical to that of the limestone facies. Carozzi and Textoris
(1967) interpreted equivalent laminated dolomites of the Indiana outcrop area as
deposits in a supratidal, pene saline, low-energy environment.
Geophysical characteristics
In the limestone area the geophysical characteristics of the Grand Tower
Limestone are quite consistent (figs. 7-14). The rather low porosity of the lime-
stone produces uniformly high electrical resistivities, neutron responses, and
sonic velocities. Electrical resistivity logs characteristically have slightly lower
resistive zones at the top, middle, and base (fig. 7, well 11). Except for the
Tioga Bentonite Bed, the spontaneous potential is uniformly high -negative, and the
natural gamma radioactivity is uniformly low.
In the dolomite area the electrical resistivities, neutron responses, and
sonic velocities are all low in response to the higher porosities. The spontane-
ous potentials and natural gamma radioactivities are comparable to those of the
southern limestone area.
LINGLE FORMATION
In the southwestern Illinois outcrop area, the Lingle Formation was defined
by Savage (1920a) to include the strata from the Microcyclus Zone at the base to
the base of the silty dolomites or dolomitic, silty limestones of the Alto Formation.
The type section designated by Savage is near Lingle School, in Sec. 26, T. 13 S.,
R. 2 W., Union County. Recent studies by Grimmer (1968) and wells in the area
indicate that only a small portion of the formation is exposed at this locality. No-
where in southwestern Illinois is the Lingle Formation completely exposed in one
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
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outcrop, although the section 3| miles west of the village of Cobden, in the NW|
NE| Sec. 34, T0 11 S., R. 2 W., Union County, is complete except for several
covered intervals, presumably of shale.
The Lingle Formation (fig. 6) includes the Howardton Limestone Member at
the base and the Tripp Limestone Member, Misenheimer Shale Member, and Walnut
Grove Limestone Member at the top. An oolite bed near the base of the Walnut
Grove Limestone Member is called the Rendleman Oolite Bed. The Misenheimer
Shale Member is the only previously named unit.
Only two members of the Lingle Formation extend more than 20 miles east-
ward from the outcrop. These are the Howardton and Tripp Members, the lower two
members of the formation. The Misenheimer Shale and Walnut Grove Members are
facies of the dark gray and black shale to the east and are only distinguishable
in and near the outcrop region.
Howardton Limestone Member
The name Howardton Limestone Member is here proposed for the lowermost
member of the Lingle Formation. The type section (Geologic Section 1) is in the
north face of an abandoned quarry in Backbone Ridge, north of Grand Tower, in the
NE^ NE| SE^ Sec. 23, T. 10 S., R. 4 W., Jackson County. The unit is named for
the town of Howardton, 2 miles east of the I type section. The type section con-
sists of 33 feet of argillaceous, brown-gray (wet and fresh), fossiliferous, fine-
grained limestone. Shaly partings are abundant. Fossils include solitary corals,
brachiopods, and crinoids.
In outcrop, the Howardton is differentiated from the underlying Grand Tower
Limestone by (1) its moderate argillaceous content versus the relatively pure lime-
stone of the Grand Tower, (2) a zone in which Microcyclus is relatively abundant
at the base of the Howardton Member, and (3) the Hamilton fossils in the Howard-
ton versus the Onondaga fossils in the Grand Tower. The lower boundary of the
Howardton coincides with the original Grand Tower- Lingle contact (Savage, 1920a,
1920b; Weller, 1944; Cooper et al., 1942; and Cooper, 1944).
The Howardton Member is less argillaceous and silty than the overlying
Tripp Limestone Member, which contains spore -bearing, calcareous shale or very
silty and argillaceous limestone, especially at the base. At the top of the Howard-
ton Member a distinctive, calcareous, intraformational microbreccia consisting of
pebble -size or smaller, irregularly shaped, light-colored limestone fragments of
diverse texture in a dark, fine-grained, calcareous matrix forms a useful and wide-
spread marker bed.
In subsurface, in the southern part of the study area, the Howardton Member
is differentiated, as in the outcrop area, on the basis of argillaceous content. It
becomes less argillaceous northward and northwestward until it can be differentiated
from the Grand Tower Limestone only by cores and geophysical logs (figs. 11 and 12)
As in the outcrop area, the member characteristically contains the intraformational
microbreccia at its top.
Thickness and distribution
The Howardton Member ranges in thickness from 0 along the flanks of the
Sparta Shelf to more than 110 feet in southeastern Illinois (fig. 15). The distribu-
tion in the southernmost part of the area nearly duplicates that of the Grand Tower
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
23
Fig. 15 - Thickness of Howardton Limestone Member
24 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
Limestone. To the north, however, the Howardton pinches out onto the Vandalia
Arch, whereas the Grand Tower continues to thicken northward (figs. 13 and 14).
The occurrence of the Tioga Bentonite Bed both north and south of the arch, 10 to
2 0 feet below the Grand Tower Limestone top, supports the interpretations shown
in figures 13 and 14.
Lithology
The limestones of the Howardton Member are fossiliferous and fine to
coarse grained. Fine-grained limestone is the most abundant. Lithographic
texture, which is common in the overlying Tripp Limestone, is extremely rare.
Silt and clay are present in shale partings and are disseminated in the limestone.
Microbreccia, although present lower, is most abundant at the top of the unit,
especially near its pinch out to the north and west. Fossils, which are nearly
always present, include brachiopods, corals, crinoids, stromatoporoids, and
Tentaculites.
Phosphatic material, in the form of angular to subrounded pellets, bone
fragments, or fish scales occurs in association with the microbreccia near the
top. These are disseminated through approximately 5 feet of strata. The phos-
phatic material is a lag deposit associated with an unconformity that is probably
equivalent to the unconformity at the base of the Beechwood Member of the North
Vernon Limestone of Indiana (Butts, 1915; Dawson, 1941; Patton and Dawson, 1955;
Bluck, 1966).
The occurrence of calcareous intraformational microbreccia, stromatopo-
roids, and calcareous breccia at the top of the Howardton Member over the western
and northern areas suggests very shallow conditions and, also, probably uncon-
formity (fig. 4). Chert is rare but is found in the deeper portions of the basin.
Glauconite is extremely rare.
Geophysical characteristics
With the exception of natural electrical spontaneous potential, the geo-
physical properties of the Howardton Member are similar to those of the Grand
Tower Limestone in its southern area. Nowhere is the clay content high enough to
affect significantly the natural gamma radiation, electrical resistivity, sonic veloc-
ity, or neutron response. In fact, electrical resistivities tend to be slightly high-
er in the Howardton Member than in the underlying Grand Tower Limestone. The
spontaneous potential, however, characteristically grades from high -negative at
the base to more positive values at the top, forming an inflection point at the base
of the unit (figs. 7-14). This inflection point is the Lingle -Grand Tower contact.
As shown in cores, it marks the lowest occurrence of significant amounts of clay
and silt.
Stratigraphic relations
As shown by Meents and Swann (1965), the Lingle -Grand Tower contact in
the deeper basin area is conformable and gradational. However, in the western
and northern areas, where the formations are thinner, the contact is abrupt and
perhaps slightly disconformable. In contrast to opinions expressed by previous
workers (for example Meents and Swann, 1965; Workman, 1944), sandstone or
concentrations of sand grains do not occur at this stratigraphic position, except
on the Sparta Shelf where the Dutch Creek Sandstone Member converges with the
top of the Grand Tower Limestone (fig. 11).
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 25
In the west, toward the Sparta Shelf, and in the southwest, the Howardton
Member has about the same distribution as the Grand Tower Limestone. Toward
the north, however, the Howardton Member probably pinches out far south of the
Grand Tower Limestone, although the stratigraphic relations are not clear. To the
northwest, the contact is poorly defined and some strata included in the Grand
Tower Limestone may be equivalent to the Howardton Member.
Although the contact is somewhat irregular in outcrops and in cores, appar-
ently little erosion occurred, as shown by the occurrence of the Tioga Bentonite
Bed 10 to 20 feet below the contact over a broad area in southeastern and eastern
Illinois. Farther west, also, the Howardton Member overlies the Grand Tower in a
large area. A slight disconformity may appear near the pinch out of the units, but
thinning ot the Grand Tower is a result of overstep and shoreward convergence of
successive units more than of post-Grand Tower erosion.
Tripp Limestone Member
The name Tripp Limestone Member is here proposed for the argillaceous,
silty, cherty limestone member of the Lingle Limestone between the Misenheimer
Shale Member above and the moderately argillaceous Howardton Limestone Member
below. The type section (Geologic Section 3) is an outcrop on the south side of
Kratzinger Hollow, about 1 mile northwest of Jonesboro, in the Nj NE^ NW| Sec. 23,
T. 12 S., R. 2 W., Union County, Illinois. The upper 17 feet of the member is
exposed in the type section (fig. 16) (Grimmer, 1968, p. 410). Nearby wells indi-
cate the total thickness of the member to be about 22 feet. The member is named
for Tripp School, about 200 yards northwest of the type section.
The Tripp Member may be exposed also in the Nj NE| Sec. 34, T. 11 S.,
R. 2 W., but the strata are badly disturbed and definite identification could not be
established. No exposure of the basal contact was found.
In southwestern Illinois, the Tripp Member is characterized in its lower
half by very argillaceous and very silty limestone or very calcareous shale that
characteristically contains a number of large spores. The upper half of the mem-
ber is marked by somewhat shaly, cherty, dolomitic, glauconitic limestone.
Thickness and distribution
The Tripp Limestone Member thickens from its pinch out on the Sparta Shelf
to a maximum thickness of over 80 feet in south-central Illinois. In eastern
Illinois, it grades laterally to the Blocher Shale (figs. 16, 20, and 21). To the
west and north, the Tripp everywhere overlaps the Howardton Limestone Member.
The thickness of the Tripp Member is irregular (fig. 16). The unit is thick-
est (over 80 feet) immediately west of the facies change with the Blocher Shale
and is moderately thick (30 to 40 feet) along the north side of the facies change.
North and west from these areas the unit does not thin toward the Sparta Shelf
and Vandalia Arch as the other units do, but, instead, it thickens along an arcuate
belt that extends from T. 5 S., R. IE. (west-central part of the area), through
T. 4 N., R. 1 W., and to T. 16 N. , R. 10 W. (northeastern part of the area). This
belt of thickening is in juxtaposition with the zero line of sub-units A and B at the
base of the Sweetland Creek Shale. Approximately the upper 20 feet of the Tripp
Limestone Member in this belt may grade into the Sweetland Creek Shale.
26
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
Fig. 16 - Thickness of Tripp Limestone Member.
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 11
Lithology
The lithology of the Tripp Member is heterogeneous, including limestone,
dolomite, chert, siltstone, and shale.
Limestone.- The Tripp Member is dominantly limestone, ranging from light
to dark gray and light brownish gray to dark brownish gray. The limestones gen-
erally are argillaceous and silty, with a few containing as much as 30 or 40 per-
cent insoluble residue. In the north and west, however, terrigenous detritus is
completely lacking in some beds. The limestones range from sublithographic to
coarse grained and brecciated. Nonfossiliferous, sublithographic to fine-grained
limestone is more common toward the east and southeast, toward the Blocher Shale,
and also north of the Vandalia Arch. Fossiliferous coarser grained limestones
occur to the west and over the Vandalia Arch where quartz sand grains are also
an important constituent. Fossils include crinoids, brachiopods, and corals.
Two oolitic limestone beds occur in the westernmost and northernmost
parts of the area — one approximately 10 feet from the top of the member and the
other near the middle. The upper bed is extensive and consists of 1 mm or smaller
oolites in a light brown, sublithographic to fine-grained, calcareous matrix. It
is present immediately north and west of the limits of Sweetland Creek sub-units
C and D and occurs where the Tripp Member thickens. This situation is comparable
to that in the outcrop area where the Rendleman Oolite Bed has a facies relation
with the Sweetland Creek Shale. Although the northern oolite bed is nearly contem-
poraneous with the Rendleman Oolite Bed, they are separated by the Sparta Shelf
and cannot be traced directly to one another.
Dolomite.- Partial dolomitization of the limestone is widespread, but do-
lomite occurs within the Tripp Member only on the eastern edge of the Sparta Shelf.
In that area, dolomite comprises one-half of all the unit and is as much as 30
feet thick. The dolomite is characteristically dark brownish gray and very fine to
finely crystalline.
Chert.- Chert is an important constituent, mostly as nodules. Chert beds
are present, most noticeably in Wayne and Clay Counties (T. 2 S. and 4 N., R. 5
to 7 E.). The chert ranges from light gray to blue -gray to gray, and locally con-
stitutes as much as 30 percent of the unit.
Glauconite and phosphates.- Glauconite is abundant in the northern and
western parts of the area. Glauconite and chert are diagnostic of the Tripp Mem-
ber. Phosphate pellets have an irregular distribution. In two or three outcrops,
a bed of phosphate pellets occurs near the middle of the unit.
Shale.- Shale is most abundant at the top and the base of the Tripp Lime-
stone Member. Only near the facies contact with the Blocher Shale is the shale at
the base abundant enough to appear in chip samples. In that area, the basal unit
is 10 feet or less of dark brownish gray, very calcareous, spore-bearing shale.
Farther west, the basal shale becomes so well interbedded with limestone that it
is recognized only in geophysical logs and cores. This shale or shaly limestone
is a key bed within the Lingle Formation because it can be traced on geophysical
logs from southernmost Illinois to some distance north of the Vandalia Arch in cen-
tral Illinois.
The shale at the top of the Tripp Limestone Member marks the transition to
the overlying or adjacent Blocher Shale. It has a maximum thickness of about 5
28 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
feet and contrasts 'with the black shale of the Blocher by being very calcareous
or very dolomitic, gray or dark gray, and reacting geophysically like the under-
lying units.
Geophysical characteristics
Because of its lithologic heterogeneity, the geophysical properties of the
Tripp Limestone Member are quite variable (figs. 7-14). In general, neutron re-
sponse, sonic velocities, and electrical resistivities tend to be high, but are
more variable and average lower than in the underlying Howardton Member. Nat-
ural electrical spontaneous potential tends to be high-positive but differs con-
siderably from place to place, especially where dolomite or chert beds are plenti-
ful (figs. 10 and 11). Natural gamma radiation is slight to moderate and exhibits
the most consistency (fig. 7).
Although some units within the member exhibit geophysical properties that
can be traced for a few tens of miles, only the basal shaly unit of the member is
recognizable over most of the area. This key bed is evident on all of the geophysi-
cal traces. On electric, sonic, and neutron logs it is represented by a persistent
but subdued notch. The spontaneous potential of the key bed is on the shale line
(high- positive), and, over most of the area, it is the oldest stratum within the
Middle Devonian sequence that exhibits this high-positive spontaneous potential.
The gamma radiation of the key bed is moderate. All geophysical properties show
the shaliness to be sharply defined at the base but gradational upward. Shaliness
within the Tripp Member decreases to the north and west, and the key bed becomes
less well defined in those directions.
Stratigraphic relations
The widespread occurrence of the phosphatic, calcareous microbreccia,
which commonly marks the top of the Howardton Member, followed by the abrupt
increase in shaliness characteristic of the base of the Tripp Member, suggests a
widespread regression and subsequent transgression of the Middle Devonian sea.
The Tripp Member overlaps the Howardton Member and the Grand Tower
Limestone, and the disconformity merges on the Sparta Shelf with the pre-Middle
Devonian erosion surface. Between the Sangamon Arch in central Illinois and the
Vandalia Arch farther south, the Grand Tower Limestone extends beyond the Howard-
ton Member and is overlapped by the Tripp Member (figs. 11 and 13), but the nature
of the contact is obscure.
Misenheimer Shale Member
The Misenheimer Shale Member of the Lingle Limestone consists of approx-
imately 50 feet of dark gray, calcareous, spore-boring shale overlying the Tripp
Limestone Member and overlain by the Walnut Grove Limestone Member. The shale
was named by Savage (19 20a), who classified it as a formation and designated an
exposure in the SWj Sec. 26, T. 13 S., R. 2 W. , as the type section. Weller
(1944) and others considered the Misenheimer Shale to "be discontinuous and not
traceable, and the name was abandoned. Grimmer (1968) and the writer have suc-
ceeded in tracing it throughout the southwestern Illinois outcrop area, and it is
reinstated as a member of the Lingle Formation. Grimmer (1968) suggested the lo-
cality used here for the type section of the Tripp Limestone Member as the princi-
pal reference section of the Misenheimer Shale.
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
29
Thickness and distribution
The Misenheimer Shale occurs only in the outcrop area of southwestern
Illinois (fig. 17). The member is more than 50 feet thick in the Wittenberg Trough
and its southern extension, and it is 10 to 30 feet thick near the area where it
grades to the Sweetland Creek Shale. Like the Tripp Member, the thickness of
the Misenheimer Sh'ale is not as strongly influenced by the Wittenberg Trough
and the DuQuoin Monocline as are some of the lower units.
Lithology
The Misenheimer Shale is generally a dark gray, dark olive gray, and gray-
brown, spore -bearing shale. Limestone and chert lenses are rare. Glauconite
is rare but does occur northwest of the outcrop belt. Grimmer (1968) and Savage
(1920a, 1920b) reported a sparse fauna.
Fig. 17 - Thickness of Misenheimer
Shale Member.
Stratigraphic relations
The contact of the Misenheimer
Shale with the underlying Tripp Member
is abrupt but conformable. Grimmer
(1968, fig. 3) considers the upper con-
tact to be at the lowermost cherry bio-
clastic limestone, which includes some
shale, in the overlying member. The
writer considers the upper contact at
most localities to be marked either by
the Rendleman Oolite Bed or bioclastic
limestone at the base of. the Walnut
Grove Limestone Member. A short dis-
tance to the east of the outcrop area,
where the overlying Walnut Grove Lime-
stone is not present, the Misenheimer
Shale grades laterally into the Sweet-
land Creek Shale (fig. 17).
Walnut Grove Limestone Member
The uppermost limestone member
of the Lingle Formation is here named
the Walnut Grove Limestone Member.
It consists of approximately 40 feet of
cherty, very silty, glauconitic, spore -
bearing, fine-grained, fossiliferous
limestone. It is 29 feet thick in the
type section (Geologic Section 2), an
outcrop in a small tributary to Clear
Creek, 2 miles south of Alto Pass, in
the SE| SE-i SW| Sec. 22, T. 11 S., R.
2 W., Union County, Illinois (fig. 18).
The outcrop is near the top of a gully,
30
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
1500 feet north of the sharp bend in the
road near the center of the NW{ Sec.
27.
Thickness and distribution
The Walnut Grove Limestone
Member occurs only in the southwest-
ern Illinois outcrop area (fig. 18). It
ranges from over 5 0 feet thick in the
west, along the outcrop belt and in the
Wittenberg Trough, to less than 10 feet
west of the facies line of vertical cut-
off (fig. 18). The thicker portions of
this unit correspond to the shape of
the trough and its southern extension.
Lithology
The Walnut Grove Member con-
sists mainly of dolomitic, silty, cher-
ty limestone. The limestone is gener-
ally fine grained and fossiliferous . A
single bed of very coarse-grained, bio-
clastic limestone occurs at the base.
Fossils include crinoids, corals, brach-
iopods, and spores. The silt and clay
content of the limestones ranges from 10
to 40 percent. The bioclastic limestone
is free of silt and clay but contains fine
to medium, subrounded quartz sand
grains. Nodular chert is blue-gray to
gray and ranges from 5 to 30 percent.
Glauconite is abundant and characteris-
tic. The limestone locally is interbedded with spore -bearing, very dark brown,
calcareous shale.
The Walnut Grove Limestone Member appears to grade laterally into the
Sweetland Creek Shale a few miles east of the outcrop belt. Its contact with the
underlying Misenheimer Shale Member is at the base of a relatively pure, very
coarse-grained, bioclastic limestone that generally lies directly beneath the Ren-
dleman Oolite Bed. In general, the limestone is purer than the isolated limestone
beds, which locally occur in the underlying shale. The upper contact of the Wal-
nut Grove is sharply defined; the glauconitic, cherty limestones of the Walnut
Grove are readily distinguished from the basal dolomitic siltstone of the Alto For-
mation.
Fig. 18
Thickness of Walnut Grove
Limestone Member.
Rendleman Oolite Bed
An oolite bed near the base of the Walnut Grove Limestone Member is the
most significant key bed within the Lingle Formation in the outcrop area. The bed
occurs at all of the several significant Lingle Formation exposures and in most of
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
31
the wells in this region. The bed is here named the Rendleman Oolite Bed and the
type section is part of the Walnut Grove type section in the SE| SE^ SW{ Sec. 2 2,
T. 11 S., R. 2 W., Union County, Illinois (Geologic Section 2). The name is
derived from the Rendleman School, 1 mile east of the type section.
The Rendleman Oolite Bed is about 18 inches thick. It consists of ooliths
in a fine-grained limestone matrix. Coarse-grained matrices occur but are rare.
The ooliths are poorly sorted and have a maximum diameter of 1 mm. The fine-
grained matrix is light brown-gray to brown-gray and approaches a lithographic
texture. The fine-grained matrix indicates quiet water sedimentation, which
suggests that the oolites are allochthonous and were derived from nearby shoal
areas located to the east on the southern extension of the DuQuoin Monocline or
to the west on areas that have since been eroded.
ALTO FORMATION
The Alto Formation, overlying the Walnut Grove Limestone Member, con-
sists of over 70 feet of silty limestone
and dolomitic or calcareous siltstone.
Savage (1920a, 1920b) designated the
type section as an exposure in Sec. 34,
T. 11 S., R. 2 W., Cobden Quadrangle,
Union County, Illinois. The best ex-
posed section is in the center of the
N| NE| NE^ Sec. 34. In the subsurface
near the outcrop belt, the formation is
composed of two units: a lower dolomi-
tic siltstone and an upper silty cherty
dolomite. The Alto Formation, like
the underlying Walnut Grove Limestone
Member of the Lingle Formation, is re-
stricted to the southwestern Illinois
outcrop area (fig. 19) and, like it,
appears to grade eastward into the dark
gray and black shales of the Sweetland
Creek.
The Alto Formation is thickest
(over 70 feet) in the southern extension
of the Wittenberg Trough and gradually
thins in all directions . The formation
consists of dolomitic and calcareous
shale in the lower half and calcareous
shaly dolomite in the upper. The shale
resembles that of the Misenheimer
Shale, The dolomite is generally med-
ium to coarsely crystalline at the top,
grading downward to finely crystalline.
The color ranges from gray to dark gray-
brown. Nodular chert is abundant, es-
pecially in the upper dolomite, and is
white, gray, and black. The lower
Fig. 19 - Thickness of Alto Formation.
32
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
shale locally contains glauconite and spores. Savage (1920a, 1920b) reported
a sparse fauna. Orr (1964) reported an extensive conodont fauna from the type
section, which Collinson et al. (1967) interpreted as youngest Middle Devonian,
BLOC HER SHALE
The name Bloc her Shale was introduced by Campbell (1946) for the lower-
most carbon-rich, calcareous, or dolomitic black shale in the New Albany Group
in the southeastern Indiana outcrop. Lineback (1968) and Collinson et al. (1967)
traced the formation across Indiana into Illinois. Lineback, using lithologic cri-
teria, showed the formation to be somewhat thicker locally than did Collinson
et al., who used geophysical criteria. This report, also using geophysical cri-
teria, in general follows Collinson et al.
Thickness and distribution
The Blocher Shale is present in
Illinois in a belt 50 miles wide along
the southeastern edge of the state
(fig. 20). The shale is over 80 feet
thick in the Moorman Syncline in south-
eastern Illinois, and it thins more grad-
ually to the north than to the west (fig.
21).
Lithology
The Blocher Shale consists of
brown-black to black, somewhat cal-
careous or dolomitic, pyritic, fissile,
spore -bearing shale. The black color >
which is diagnostic of the unit, results
from a high content of carbon derived
from plants (Lineback, 1968).
Geophysical characteristics
The Blocher Shale is best de-
fined on sonic, neutron, and gamma ray
logs. Electrical resistivity is high, and
natural spontaneous potential is hi-gh-
positive, similar to units below and
above. In terms of neutron response,
gamma radiation, and sonic velocity,
the unit is intermediate between non-
calcareous shale and pure limestone.
These properties also consistently in-
dicate a higher carbonate content at
the top than at the base of the shale.
Fig. 20 - Thickness of Blocher Shale,
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
33
/*"* -W """*" i.
Fig. 21 - Combined thickness of Tripp Limestone Member of the Lingle Formation
and the Blocher Shale and the percentage of black shale.
34 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
Stratigraphic relations
Through much of south-central Illinois the Blocher Shale appears to grade
laterally into the Tripp Limestone Member. The change is quite abrupt in the
south -central area but more gradual to the north (figs. 7, 8, 9, 14, and 21). In
both regions, however, the area of shale deposition expanded with time so that
the Blocher Shale transitionally overlaps the Tripp Limestone Member in a belt 2 0 to
40 miles wide. Blocher-type shale within the Tripp Limestone Member is most abun
dant near the top and base. In the Blocher, limestone beds are relatively common
toward the top. The lithologic distinction between the two units is not only one of
limestone versus shale, but of carbon -poor versus carbon-rich. Lineback (1968)
reports as much as 50 percent carbonate in the Blocher Shale in Indiana. The in-
termediate geophysical characteristics of the unit in terms of shale versus lime-
stone support this viewpoint.
SWEETLAND CREEK SHALE
The greenish gray shale at the base of the New Albany Shale Group was
named Sweetland Creek Shale in southeastern Iowa by Udden (1899), but the name
was discontinued in Illinois by Workman and Gillette (1956). James (1965) traced
the unit from the type area to southern Illinois, and Collinson et al. (1967) ex-
tended the term to southern Illinois. Tracing of key beds shows that the Sweetland
Creek Shale in western Illinois is younger, for the most part, than the Sweetland
Creek to the southeast (fig. 4). These key bed correlations show that to the
southeast the gray shale of the type Sweetland Creek grades to the black shale
of the Grassy Creek (figs. 11-13) and that the Sweetland Creek Shale of the south-
eastern area either grades laterally to the Tripp Limestone Member or thins over
it to the north and west.
Thickness and distribution
In southern Illinois the Sweetland Creek Shale ranges from over 2 00 feet
thick in the Moorman Syncline area of southeastern Illinois to its pinch out on the
southern part of the Sparta Shelf (fig. 2 2). It averages 20 feet thick in the area
north of the Vandalia Arch. These thickness changes mostly result from lateral
thinning toward the basin margins. However, thickening from central to northern
and western Illinois is along the line of vertical cutoff where the Sweetland Creek
Shale thickens at the expense of the Grassy Creek Shale.
Lithology
The Sweetland Creek Shale, in the deeper part of the basin, consists of
brownish black to dark gray shale. The formation becomes lighter colored upward.
Differences in color and organic content between the Sweetland Creek and the un-
derlying Blocher Shale are so subtle that the units are difficult to distinguish on the
basis of samples. To the north and west, the dark gray gives way to gray and
green-gray.
Geophysical characteristics
For the most part, the Sweetland Creek Shale has geophysical properties
typical of none ale areous, low-organic shale. The sonic velocities and neutron
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
35
Fig. 22 - Thickness of Sweetland Creek Shale. The northern vertical cutoff is
where the Sweetland Creek thickens northward and westward at the
expense of the Grassy Creek Shale (figs. 4, 11, and 13); the southern
vertical cutoff is where the Sweetland Creek grades laterally into the
Lingle and Alto Formations (figs. 4 and 6).
36 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
response are low, natural gamma radiation is high, and natural electrical spon-
taneous potential is high-positive. The electrical resistivity is irregular but is
dominantly low.
Irregularities in electrical resistivity within the Sweetland Creek are so
uniform throughout the study area that it is possible to trace approximately a doz-
en key beds for many miles. These key beds are boundaries of alternating highl-
and low-resistive units. They also appear on the sonic, neutron, and gamma ray
logs. The more resistive units show slightly lower neutron response, slightly
lower sonic velocities, and slightly higher natural gamma radiation than the less
resistive units. Key beds are used to differentiate six sub-units; the five lower
sub-units are labeled. A through E on the cross sections. The upper sub-unit con-
sists of the strata that grade laterally to the Grassy Creek Shale (figs. 7-14).
Stratigraphic relations
In southwestern Illinois the Sweetland Creek Shale is interpreted as grad-
ing laterally into the Lingle and Alto Formations and, therefore, is not present in
the outcrop area. Farther north, on the Sparta Shelf, the uppermost part of the
unit overlaps Middle Devonian carbonate strata and is present in most of western
Illinois. On the southern, more active, part of the Sparta Shelf, the shale pinches
out (fig. 22).
As shown by geophysical logs, the Sweetland Creek -Blocher contact is
abrupt; the high carbonate and organic contents of the Blocher Shale markedly con-
trast with the lesser amounts of those components in the Sweetland Creek Shale.
The lowest unit within the Sweetland Creek Shale (sub-unit A) thins noticeably
from east to west in the area of Blocher Shale occurrence, apparently because of
internal thinning within sub-unit A rather than facie s relations with the Blocher
Shale (figs. 8 and 9).
Subsurface stratigraphic relations between the Sweetland Creek Shale and
the Lingle Formation are very complex. Each succeeding Sweetland Creek Shale
sub-unit overlaps the underlying one (fig. 23); also, each sub-unit thins toward
its pinch out to the west and north. Conversely, the Tripp Limestone Member
thickens, and an oolite bed, which may correlate with the Rendleman Oolite Bed,
appears near the top of the member immediately west and north of the pinch out of
the younger Sweetland Creek sub-units (figs. 16 and 23). Thus, the Sweetland
Creek Shale, in part, may have a facies relation with the Tripp Limestone Member.
In some areas a facies relation is supported by a transition zone; in others, the
contact is sharp.
In the area of the oolite occurrences and to the west and north, the contact
becomes unconformable and is marked by scattered occurrence of the Sylamore
Sandstone (Workman and Gillette, 1956). Although the Sylamore Sandstone over-
lies Middle Devonian rocks in many areas in central and western Illinois, it occurs
only sporadically in the study area. It commonly consists of St. Peter-type quartz
sand cemented by pyrite, calcite, and dolomite. It overlies the Tripp Limestone
Member of the Lingle Formation in the northeastern part of the area, and it occurs
as a thin, sandy shale or clayey sand on top of the Alto Formation in the outcrop
area in southwestern Illinois. In subsurface, the Sylamore is difficult to dis-
tinguish and consequently is not indicated in the cross sections.
Although the evidence is not entirely conclusive, the Sweetland Creek
Shale in southwestern Illinois appears to have a facies relation with the Misen-
heimer Shale and Walnut Grove Limestone Members of the Lingle Formation and
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS
37
£:::::! Upper Unit
eS d [ i
ES3 c
VT~K Blocher Shale
MILES
q_ 20
Fig. 23 - Units in contact with the top of the Middle Devonian limesto:
38 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
with the Alto Formation. This gradation results from the addition of carbonate
in southwestern Illinois, which "dilutes" the eastward -derived clay and very fine-
grained silt. The terrigenous detritus within these units is identical. The position
of the zone of transition (figs. 17, 18, 19, and 22) is not accurately known, but
the carbonate content of the strata is already low at the east side of T. 11 and 12
S., R. 1 W., just 6 miles east of the outcrop.
In addition to a gradational contact with the Grassy Creek Shale, the Sweet-
land Creek Shale grades laterally into the lower part of the Grassy Creek Shale in
central Illinois. A vertical cutoff, in the area of transition, extends in a semicircle,
convex toward the north from the west-central part of the study area to the north-
east part (fig. 22). About 20 feet of strata are involved in the facies change from
black shale with high carbon content in the south to lighter colored gray and green-
gray shale with low carbon content to the north and west. The change is well de-
fined by low resistivity to the north and west and high resistivity to the southeast.
The facies boundary is arbitrarily drawn where the strata involved exhibit off- scale
electrical resistivity (on the 0 to 100 ohms m2/m scale) (figs. 11 and 13).
GEOLOGIC HISTORY
Beginning with sandstone and sandy limestone at the base of the Grand
Tower Limestone, deposition during the Middle Devonian was characterized by
two important transgressions and one important regression. The Dutch Creek
Sandstone Member at the base of the Grand Tower Limestone marks the initial
transgression over the pre -Middle Devonian erosion surface. In southern Illinois
this unconformity is the base of the Kaskaskia Sequence and is associated with a
craton-wide emergence. The transgression was accompanied by shallow- water car-
bonate deposition south of the Vandalia Arch, dolomite on the arch, and lithographic
limestone between it and the Sangamon Arch. The only terrigenous detritus within
the Grand Tower Limestone is fine to coarse, rounded sand grains of the St. Peter
type derived from the Ozark uplift to the west. The carbonate shelf environment
extends into the Wittenberg Trough where subsidence allowed the accumulation of
an abnormally thick sequence.
The carbonate shelf was subsequently invaded by mud derived from the
Appalachian area to the east. The Howardton Limestone Member at the base of the
Lingle Formation shows the same carbonate microfacies as the Grand Tower Lime-
stone, but mud and very fine-grained silt are added. Quartz sand deposition was
confined to areas north of the Vandalia Arch, except along the western side of the
Wittenberg Trough in a locality that was well isolated from the deeper basin to the
east. The Howardton Member is a regressive deposit, with the unconformable upper
surface marked by a calcareous intraformational microbreccia.
A limestone -producing oxygenated environment existed to the west during
deposition of the Tripp Limestone Member and an organic -rich reducing environ-
ment lay to the east, producing the Blocher Shale B Abundant chert and sublitho-
graphic limestone in the Tripp Limestone Member in the zone of transition con-
trasts with fossiliferous limestone to the west and calcareous shale to the east,
reflecting a lateral change from oxygenated conditions to a reducing environment.
Although the lighter color of the shales of the Sweetland Creek Shale indi-
cates lower organic content, these shales contain virtually no carbonates. Carbon-
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 39
ates are only present shoreward to the west, where the shales intertongue with
the upper strata of the Tripp Limestone Member. These carbonates are shallow-
water types and mark shoal areas. The youngest Sweetland Creek Shale over-
lapped the upper carbonates of the Tripp Member and was deposited on pre -Middle
Devonian strata.
REFERENCES
Bluck, B. J., 1966, Petrography of Devonian phosphates of Indiana: Illinois
Acad. Sci. Trans., v. 59, no. 1, p. 43-47.
Butts, Charles, 1915, Geology and mineral resources of Jefferson County, Ken-
tucky: Kentucky Geol. Survey, ser. 4, v. 3, pt. 2, 270 p.
Campbell, Guy, 1946, New Albany Shale: Geol. Soc . America Bull. , v. 57,
no. 9, p. 829-908.
Carozzi, A. V., and D. A. Textoris, 1967, Paleozoic carbonate microfacies of
the Eastern Stable Interior (U.S.A.): E.J. Brill, Leiden, Netherlands,
41 p.
Collinson, Charles, L. E. Becker, G. W. James, J. W. Koenig, and D. H. Swann,
1967, Devonian of the north-central region, United States - Illinois Basin,
in International symposium on the Devonian System: Alberta Soc. Petro-
leum Geologists, Calgary, Alberta, Canada, v. 1, p. 940-962.
Cooper, G. A., 1944, Remarks on correlation of Devonian formations in Illinois
and adjacent states: Illinois Geol. Survey Bull. 68-A, p. 214-216.
Cooper, G. A., et al., 1942, Correlation of the Devonian sedimentary formations
of North America: Geol. Soc. America Bull., v. 53, p. 1729-1794.
Croneis, Carey, 1944, Devonian of southeastern Missouri: Illinois Geol. Survey
Bull. 68, p. 103-131.
Dake, C. L., 1918, The sand and gravel resources of Missouri: Missouri Bur.
Geol. and Mines, v. 15, 2nd ser., 274 p.
Dawson, T. A., 1941, The Devonian formations of Indiana, Part I, Outcrop in
southern Indiana: Indiana Dept. of Conserv., Div. Geology, 48 p.
Grimmer, J. C, 1968, Stratigraphy of the Middle Devonian shales of southern
Illinois: Illinois Acad. Sci. Trans., v. 61, no. 4, p. 407-415.
40 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
James, G. W., 1965, Age and distribution of the Late Devonian Sweetland Creek
Shale in western Illinois: Univ. Illinois [Urbana] unpubl. Honors thesis.
Keyes, C. R., 1894, Paleontology of Missouri (Part I): Missouri Geol. Survey
Rept., v. 4, 271 p.
Lineback, J. A., 1968, Subdivisions and depositional environments of New Albany
Shale (Devonian-Mississippian) in Indiana: Am. Assoc. Petroleum
Geologists Bull., v. 52, no. 7, p. 1291-1303.
Meents, W. F., and D. H. Swann, 1965, Grand Tower Limestone (Devonian) of
southern Illinois: Illinois Geol. Survey Circ. 389, 34 p.
Orr, R. W., 1964, Conodonts from the Devonian Lingle and Alto Formations of
southern Illinois: Illinois Geol. Survey Circ. 361, 2 8 p.
Patton, J. B., and T. A. Dawson, 19 55, Stratigraphy: Indiana Geol. Survey
Field Conf. Guidebook 8, p. 37-43.
Savage, T. E., 1910, The Grand Tower (Onondaga) Formation of Illinois, and its
relation to the Jeffersonville beds of Indiana: Illinois Acad. Sci. Trans.,
v. 3, p. 116-132.
, 1920a, The Devonian formations of Illinois: Am. Jour. Sci.,
4th ser., v. 49, p. 169-182.
, 1920b, Geology and economic resources of the Jonesboro quad-
rangle: Illinois Geol. Survey unpubl. rept. TES-3, 187 p.
, 1925, Comparison of the Devonian rocks of Illinois and Missouri:
Jour. Geology, v. 33, no. 5, p. 550-558.
Schwalb, H. R., 1955, The Geneva (Middle Devonian) Dolomite in Illinois:
Illinois Geol. Survey Circ. 204, 7 p.
Sloss, L. L., 1963, Sequences in the cratonic interior of North America: Geol.
Soc. America Bull., v. 74, p. 93-114.
Swann, D. H., and H. B. Willman, 1961, Megagroups in Illinois: Am. Assoc.
Petroleum Geologists Bull., v. 45, no. 4, p. 471-483.
Udden, J. A., 1899, The Sweetland Creek Beds: Jour. Geology, v. 7, p. 65-78
Warthin, A. S., Jr., and G. A. Cooper, 1944, Middle Devonian subsurface for-
mations in Illinois: Am. Assoc. Petroleum Geologists Bull., v. 28,
p. 1519-1527.
Weller, J. M., 1944, Devonian System in southern Illinois: Illinois Geol. Sur-
vey Bull. 68-A, p. 89-102.
Weller, Stuart, and Stuart St. Clair, 1928, Geology of Ste . Genevieve County,
Missouri: Missouri Bur. Geol. and Mines, ser. 2, v. 22, 362 p.
Whiting, L. L., and D. L. Stevenson, 1965, The Sangamon Arch: Illinois Geol.
Survey Circ. 3 83, 2 0 p.
Workman, L. E., 1944, Subsurface geology of the Devonian in Illinois: Illinois
Geol. Survey Bull. 68, p. 189-199.
Workman, L. E., and Tracey Gillette, 1956, Subsurface stratigraphy of the Kin-
derhook Series in Illinois: Illinois Geol. Survey Rept. Inv. 189, 46 p.
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 41
APPENDIX A
List of Wells Used in Compiling Cross Sections
1. Lambert No. 1 Hagler, Sec. 28, T. 10 S., R. 2 W. , Jackson County, Illinois.
2. Sturdevant No. 1 State Pond Land, Sec. 14, T. 12 S., R. 2 W. , Union County, Illinois.
3. McRauer No. 4 City of Jonesboro, Sec. 25, T. 12 S., R. 2 W., Union County, Illinois.
4. Landers No. 1 Dillow, Sec. 31, T. 12 S., R. 1 W., Union County, Illinois.
5. Rigney No. 1 Hileman, Sec. 21, T. 13 S., R. 1 W., Union County, Illinois.
6. Vaughn No. 1 Ragsdale, Sec. 18, T. 14 S., R. IE., Pulaski County, Illinois.
7. Mid-Continent No. 1-A Herren, Sec. 12, T. 14 S., R. 1 E., Pulaski County, Illinois.
8. Benedum-Trees No. 1 Cavitt, Sec. 24, T. 11 S., R. 3 E., Johnson County, Illinois.
9. Texaco No. 2 Hicks-Russell Comm. , Sec. 27, T. 6 S., R. 6 E. , Hamilton County, Illinois.
10. Mitchell No. 1 Snead Comm., Sec. 14, T. 4 S., R. 7 E., Hamilton County, Illinois.
11. Nation No. 2 Mcintosh, Sec. 31, T. 3 S., R. 8 E., White County, Illinois.
12. Collins No. 1 Harris Comm., Sec. 28, T. 2 S., R. 9 E., Wayne County, Illinois.
13. Taylor No. 1 Winter, Sec. 36, T. 4 S., R. 9 E. , White County, Illinois.
14. Horton No. 1 Cuthbertson, Sec. 33, T. 2 S., R. 7 E., Wayne County, Illinois.
15. Beard No. 1 Atteberry, Sec. 21, T. 2 S., R. 7 E., Wayne County, Illinois.
16. Weinert No. 10 McPherson, Sec. 3, T. 2 S., R. 7 E., Wayne County, Illinois.
17. Peake No. 1 Feathers, Sec. 14, T. 2 S., R. 6 E., Wayne County, Illinois.
18. Texaco NCT-1 No. 5 Fuhrer, Sec. 28, T. IS., R. 6 E., Wayne County, Illinois.
19. Texas No. 1 Draper, Sec. 8, T. 3 S., R. 6 E., Wayne County, Illinois.
20. Sun No. 1 Aydt, Sec. 1, T. 4 S., R. 4 E., Jefferson County, Illinois.
21. Brehm No. 1 Hutchcraft, Sec. 24, T. 5 S., R. 4 E., Franklin County, Illinois.
22. Athene No. 1 Williford-Bosworth, Sec. 10, T. 3 S., R. 3 E., Jefferson County, Illinois.
23. Magnolia No. 1 Jones, Sec. 10, T. 3 S., R. 2 E., Jefferson County, Illinois.
24. Magnolia No. 7 Eubank-Winesburgh, Sec. 1, T. 3 S., R. 1 E., Jefferson County, Illinois.
25. National Assoc. No. 1 Schemming, Sec. 18, T. 3 S., R. 1 E., Jefferson County, Illinois.
26. Ohio No. 1 Sawyer, Sec. 33, T. 2 S., R. 1 W., Washington County, Illinois.
27. National Assoc. No. 1 Bookout, Sec. 18, T. 1 N., R. 5 E. , Wayne County, Illinois.
28. White No. 1 Colclasure, Sec. 23, T. 3 N., R. 5 E. , Clay County, Illinois.
29. Cooperative No. 1 Vangeison "A," Sec. 15, T. 5 N., R. 5 E., Clay County, Illinois.
30. Wiggins No. 1 Genaust, Sec. 18, T. 7 N., R. 6 E., Effingham County, Illinois.
31. National Assoc. No. 3 Krogmann, Sec. 31, T. 9 N., R. 7 E., Cumberland County, Illinois.
32. Robison No. 1 Young, Sec. 8, T. 10 N., R. 7 E., Cumberland County, Illinois.
33. Duncan No. 9 Oliver, Sec. 2, T. 12 N., R. 7 E., Coles County, Illinois.
34. Carter No. 1 Cobb, Sec. 10, T. 13 N., R. 7 E., Coles County, Illinois.
35. Sanders No. 1 Daily, Sec. 25, T. 14 N., R. 7 E. , Coles County, Illinois.
36. Drake and Dome No. 1 Maxwell, Sec. 3, T. 5 N., R. 12 W., Crawford County, Illinois.
37. Ohio No. 1 McKee, Sec. 29, T. 7 N., R. 13 W., Crawford County, Illinois.
38. Wilson No. 1 Rue, Sec. 27, T. 9 N., R. 10 E., Cumberland County, Illinois.
39. Tri-Apco No. 1 Holsapple, Sec. 16, T. 9 N., R. 9 E., Cumberland County, Illinois.
40. Slagter No. 1 Layton, Sec. 20, T. 10 N., R. 8 E., Cumberland County, Illinois.
42 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
APPENDIX B
Geologic Sections
1.— Backbone North Section
North face of abandoned quarry, 350 feet northwest of the road through Backbone
Ridge, HEk, NE^ SE% Sec. 23, T. 10 S., R. 4 W., Jackson County, Illinois (Altenberg 7^-minute
Quadrangle). Description based in part on samples collected by W. W. Hallstein in 1949.
The upper 10 feet is poorly exposed. Type section of Howardton Limestone Member of Lingle
Formation.
Devonian System Thickness
Lingle Formation (feet)
Tripp Limestone Member
Shale, grayish brown to dark grayish brown, very calcareous, few spores,
fossiliferous (brachiopods) 1.5
Limestone, very fine grained, grayish brown to dark gray, very argillaceous,
very silty, partly leached; contains many spores 7.0
Shale, very calcareous, grayish brown; contains abundant spores 0.5
Limestone, very fine grained, light brownish gray, silty, argillaceous,
partly leached 1.0
Total Tripp Member. . . 10.0
Howardton Limestone Member
Limestone, fine grained, brownish gray, argillaceous, silty; contains
silicified corals, some phosphatic fragments 1.0
Limestone, fine grained, brownish gray, slightly argillaceous, silty; contains
silicified corals 5
Limestone, fine grained, some pelletoidal, brownish gray, silty 1.5
Limestone, fine grained, light brownish gray to brownish gray, silty; contains
silicified corals, few phosphatic fragments 3.5
Limestone, fine grained, gray to brownish gray, silty to sandy, fossiliferous. . . . 1.0
Limestone, very fine grained, to sublithographic, slightly argillaceous, gray
to brownish gray; contains thin shale partings 2.0
Limestone, fine grained, fossiliferous, brownish gray, silty, argillaceous;
contains thin shale partings 5.0
Limestone, fine grained, fossiliferous, argillaceous, brownish gray; contains
thin shale partings 2.5
Limestone, lithographic, brownish gray 0.5
Limestone, fine grained, fossiliferous, argillaceous, light brownish gray to
brownish gray; contains thin shale partings 8.5
Limestone, lithographic, fossiliferous, dark gray to brownish gray; contains
thin shaly partings 1.5
Limestone, very fine grained, fossiliferous, brownish gray, partly leached,
silty, argillaceous; contains Microcyclus, thin shaly partings 5.5
Total Howardton Member. . .33.0
Grand Tower Limestone
Limestone, fine grained, very fossiliferous, brownish gray, partly leached 2.0
Limestone, fine grained, silty to sandy, brownish gray, sparingly fossiliferous. . . 6.0
Limestone, fine grained, gray to brownish gray, silty; contains white to light
gray chert in upper 5 feet 7.0
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 43
Thickness
Grand Tower Limestone (cont.) (feet)
Limestone, fine grained, fossiliferous, light brownish gray, silty to
sandy; contains some intraclasts 8.5
Limestone, bioclastic, fine-grained matrix; contains clasts, Chonetes _
Total Grand Tower Limestone. . . 23.5
Base of measured section is about 40 feet above base of quarry.
2. -Walnut Grove School Section
Outcrop near top of gully, on the south line, 1000 feet from west line, of Sec. 22,
T. 11 S., R. 2 W., Union County, Illinois (Cobden 7%-minute Quadrangle). Type section of
Walnut Grove Limestone Member of the Lingle Formation.
Devonian System
Alto Formation
Limestone, fine grained, very silty, glauconitic, irregularly thin to medium
bedded; contains dark gray to black chert nodules 1.0
Covered 0.5
Chert, dark gray to black, and limestone, fine grained, argillaceous, silty 1.0
Covered 0.5
Chert, dark-gray to black, and limestone, fine grained, glauconitic, very silty;
contains abundant spores 1.0
Covered 6.5
Total Alto Formation. . . 10. s
Lingle Formation
Walnut Grove Limestone Member
Limestone, fine to coarse grained, fossiliferous (biomicrite to biosparite) ,
grayish brown, glauconitic, sandy, irregularly thin to medium bedded;
contains abundant crinoids, brachiopods, and spores 5
Limestone, fine grained, dark gray, silty, very argillaceous, glauconitic,
irregularly thin to medium bedded 5
Limestone, fine grained, fossiliferous, dark gray to dark grayish brown,
glauconitic, dolomitic, irregularly thin to medium bedded; contains black
chert nodules, abundant spores, and abundant sponge spicules in some beds. ... 10.0
Covered 1.0
Limestone, fine grained, dark grayish brown, very argillaceous, very silty,
sponge spicules, thin bedded to laminated 7.0
Covered Z.O
Limestone, fine to coarse grained, coarser toward top, fossiliferous, dark
brownish gray, silty; dolomitic in lower 6 inches 1.5
Limestone, fine grained, dark brownish gray, very silty, irregularly thin to
medium bedded; contains silicified fossils 1.0
Limestone, oolitic, brownish gray; oolites are 1 mm in diameter and less in
fine- to coarse-grained matrix (Rendleman Oolite Bed) 1.5
Limestone, medium grained, crystalline, gray, glauconitic, very sandy, massive . . . 4.0
Total Walnut Grove Member. . . 29.0
44 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 441
Thickness
Misenheimer Shale Member (feet)
Shale, very calcareous, silty; contains spores 4.04-
Section below poorly exposed.
3.— Tripp School Section
Outcrop 200 feet south of the bridge on Illinois Highway 146, N% NE^ NW^ Sec. 23,
T. 12 S., R. 2 W., Union County, Illinois (Jonesboro 7%-minute Quadrangle). The strata dip
about 5° to the east, and successively younger strata are exposed eastward along an abandoned
roadcut. The Rendleman Oolite Bed is exposed in a gully, 400 feet southeast of the bridge
and about 30 feet above the level of the road. Type section of Tripp Limestone Member.
Devonian System
Lingle Formation
Walnut Grove Limestone Member
Limestone, fine grained, grayish brown, argillaceous, thin to thick bedded;
contains small very dark gray chert nodules, few crinoids 4.0
Limestone, coarse to fine grained, very fossiliferous, gray to grayish brown,
massive 2.0
Limestone, fine grained, dark brownish gray, very glauconitic, silty, thin bedded. . .5
Limestone, oolitic, brownish gray, poorly exposed; oolites are 1 mm in
diameter and less in fine- to coarse-grained matrix; base not exposed 5
Total Walnut Grove Member. . . 7.0
Covered 15.0
Mlsenheimer Shale Member
Siltstone, olive-gray, very calcareous; grades to very calcareous at base;
contains spores 6.5
Limestone, brownish gray, fine grained, silty; abundant black chert nodules 1.0
Covered 6.0
Shale, very calcareous, very dark gray, silty; contains spores .5
Covered 1.5
Limestone, fine to coarse grained, brownish gray to dark brownish gray;
fossiliferous (crinoids), silty; contains black chert nodules 1.0
Covered 3.0
Shale, calcareous, very dark grayish brown; basal contact gradational 17.0
Total Misenheimer Shale. . . 36.5
Tripp Limestone Member
Limestone, fine grained, very dark grayish brown, very silty, very argillaceous,
unevenly thin bedded 2.0
Limestone, fine grained, fossiliferous, dolomitic, very silty, irregularly
thin to medium bedded; contains blue-gray to brownish gray chert nodules 3.0
Limestone, fine grained, very dolomitic, dark grayish brown, silty, irregularly
thin to medium bedded; contains blue-gray to brownish gray chert nodules 4.0
Limestone, fine grained, fossiliferous, dark grayish brown, dolomitic, very
argillaceous, silty, massive to thick bedded; contains crinoids, Tentaculites,
and phosphatic pellets at base 2*°
MIDDLE DEVONIAN STRATA OF SOUTHERN ILLINOIS 45
Thickness
Tripp Limestone Member (cont.) (feet)
Shale, very calcareous, dark grayish brown, argillaceous; contains black
nodules of chert at top 6.0
Total Tripp Member. . . 17.0
Covered 12.0
Howardton Limestone Member
Limestone, poorly exposed, fine grained, fossiliferous (solitary corals including
Microcyclus are common), grayish brown, argillaceous, silty; contact not
exposed 0.5
Total Howardton Member. . . 0.5
Grand Tower Limestone
Limestone, fine grained, crinoidal, grayish brown to light brownish gray 3.0
Limestone, fine to medium grained, crinoidal, gray to brownish gray 2.0
Limestone, fine grained, very fossiliferous (crinoids and brachiopods
abundant), grayish brown to light brownish gray 9.0
Limestone, fine grained, fossiliferous (crinoids very abundant), argillaceous.
Base concealed at stream level 3.0
Total Grand Tower Limestone. . . 17.0
Illinois State Geological Survey Circular 441
48 p., 23 figs., app., 2800 cop., 1969
Printed by Authority of State of Illinois, Ch . 127, IRS, Par. 58.25
ILLINOIS STATE GEOLOGICAL SURVEY
ItAL dUIlY
L 1 Urbana, Illinois 61801
JOHN C. FRYE,
Ph.D. , D.Sc. , Chief
Hubert E. Risser,
Ph.D. , Assistant Chief
FULL TIME STAFF
April 15, 1969
R. J. Helfinstine, M.S., Administrative Engineer
G. R. Eadie, M.S., E.M., Asst. Administrative Engineer
Velda A. Millard, Fiscal Assistant to the Chief
Helen E. McMorris, Secretary to the Chief
GEOLOGICAL GROUP
Jack A. Simon, M.S., Principal Geologist
M. L. Thompson, Ph.D., Principal Research Geologist
Frances H. Alsterlund, A.B., Research Assistant
COAL
M. E. Hopkins, Ph.D., Geologist and Acting Head
William H. Smith, M.S., Geologist
Kenneth E. Clegg, M.S., Associate Geologist
Heinz H. Damberger, D.Sc, Associate Geologist
Harold J. Gluskoter, Ph.D., Associate Geologist
Russel A. Peppers, Ph.D., Associate Geologist
John A. Bell, Ph.D., Assistant Geologist
Roger B. Nance, M.S., Assistant Geologist
STRATIGRAPHY AND AREAL GEOLOGY
H. B. Willman, Ph.D. , Geologist and Head
Elwood Atherton, Ph.D., Geologist
T. C. Buschbach, Ph.D., Geologist
Charles Collinson, Ph.D., Geologist
Herbert D. Glass, Ph.D., Geologist
Lois S. Kent, Ph.D., Associate Geologist
Jerry A. Lineback, Ph.D., Associate Geologist
Alan M. Jacobs, Ph.D., Assistant Geologist
Susan R. Avcin, B.A., Research Assistant
ENGINEERING GEOLOGY AND TOPOGRAPHIC MAPPING
W. Calhoun Smith, Ph.D., Geologist in charge
Paul B. DuMontelle, M.S., Assistant Geologist
Patricia M. Moran, B.A., Research Assistant
GEOLOGICAL RECORDS
Vivian Gordon, Head
Hannah Kistler, Supervisory Technical Assistant
Margaret J. Weatherhead , Research Assistant
Constance Armstrong, Technical Assistant
Dorothy A. Ireland, Technical Assistant
Connie L. Maske, B.A., Technical Assistant
Mary C. Price, Technical Assistant
Elizabeth Speer, Technical Assistant
Rebecca J. Veenstra, Technical Assistant
CLAY RESOURCES AND CLAY MINERAL TECHNOLOGY
W. Arthur White, Ph.D., Geologist and Head
Bruce F. Bohor, Ph.D., Associate Geologist
Cheryl W. Adkisson, B.S., Research Assistant
GROUND-WATER GEOLOGY AND GEOPHYSICAL EXPLORATION
Robert E. Bergstrom, Ph.D., Geologist and Head
Merlyn B. Buhle, M.S., Geologist
George M . Hughes, Ph.D., Associate Geologist
John P. Kempton, Ph.D., Associate Geologist
Keros Cartwright, M.S., Assistant Geologist
Carl G. Davis, B.S., Assistant Geologist
Manoutchehr Heidari, M.S., Assistant Engineer
PaulC. Heigold, M.S., Assistant Geophysicist
Jean I. Larsen, M.A., Assistant Geologist
Murray R. McComas, M.S., Assistant Geologist
Kemal Piskin, M.S., Assistant Geologist
Frank B. Sherman, Jr., M.S., Assistant Geologist
Shirley A. Masters, B.S., Research Assistant
Verena M. Colvin, Technical Assistant
Stephen S. Palmer, Technical Assistant
OIL AND GAS
Donald C. Bond, Ph.D., Head
Lindell H. Van Dyke, M.S., Geologist
Thomas F. Lawry, B.S., Associate Petrol. Engineer
R. F. Mast, M.S., Associate Petrol. Engineer
Wayne F. Meents, Associate Geological Engineer
Hubert M. Bristol, M.S., Assistant Geologist
Richard H. Howard, M.S., Assistant Geologist
David L. Stevenson, M.S., Assistant Geologist
Jacob Van Den Berg, M.S. , Assistant Geologist
Albert L. Meyers, B.S., Research Assistant
INDUSTRIAL MINERALS
James C. Bradbury, Ph.D., Geologist and Head
James W. Baxter, Ph.D., Associate Geologist
Richard D. Harvey, Ph.D., Associate Geologist
Norman C. Hester, Ph.D., Assistant Geologist
GEOLOGICAL SAMPLES LIBRARY
RobertW. Frame, Superintendent
J. Stanton Bonwell, Technical Assistant
Eugene W. Meier, Technical Assistant
Dora Ann Reed, Technical Assistant
Charles J. Zelinsky, Technical Assistant
Ruth C. Lynge, Technical Assistant
COAL CHEMISTRY
G. Robert Yohe, Ph.D.
CHEMICAL GROUP
Glenn C. Finger, Ph.D., Principal Chemist
Thelma J. Chapman,
Chemist and Head
PHYSICAL CHEMISTRY
Josephus Thomas, Jr., Ph.D., Chemist and Head
Robert N. Leamnson, M.S., Assistant Chemist
ORGANIC GEOCHEMISTRY
G. C. Finger, Ph.D., Acting Head
Donald R. Dickerson, Ph.D., Associate Chemist
Richard H. Shiley, M.S., Assistant Chemist
Gilbert L. Tinberg, Technical Assistant
.A., Technical Assistant
CHEMICAL ENGINEERING
H. W. Jackman, M.S.E., Chemical Engineer and Head
R. J. Helfinstine, M.S., Mechanical Engineer
H. P. Ehrlinger III , M.S., E.M., Assoc. Minerals Engineer
Lee D. Arnold, B.S., Assistant Engineer
W. G. ten Kate, M.S., Geol. D. , Assistant Mineralogist
Walter E. Cooper, Technical Assistant
Robert M. Fairfield, Technical Assistant
John P. McClellan, Technical Assistant
Edward A. Schaede, Technical Assistant (on leave)
(Chemical Group continued on next page)
CHEMICAL GROUP (Continued)
ANALYTICAL CHEMISTRY
Neil F. Shimp, Ph.D. , Chemist and Head
William J. Armon, M.S., Associate Chemist
Charles W. Beeler, M.A., Associate Chemist
Rodney R. Ruch, Ph.D., Associate Chemist
John A. Schleicher, B.S., Associate Chemist
Larry R. Camp, B.S., Assistant Chemist
David B. Heck, B.S., Assistant Chemist
B.S
L. R. Henderson
Stephen M. Kim, B
John K. Kuhn, B.S.
Ru-tao Kyi, Ph.D. ,
Sharon L. Olson, E
Paul E. Gardner, Technical Assistant
George R. James, Technical Assistant
Assistant Chemist
A. , Assistant Chemist
Assistant Chemist
Assistant Chemist
S. , Special Research Assistant
W. L. Busch, A.
MINERAL ECONOMICS GROUP
Hubert E. Risser, Ph.D., Principal Mineral Economist
Associate Mineral Economist Robert L. Major, M.S., Assistant Mineral Economist
ADMINISTRATIVE GROUP
George R. Eadie, M.S., E.M., Administrator
Mary M. Sullivan, Supervisory Technical Assistant
EDUCATIONAL EXTENSION
David L. Reinertsen, A.M. , Associate Geologist in charge
George M. Wilson, M.S., Geologist
William E. Cote, M.S., Assistant Geologist
Helen S. Johnston, B.S., Technical Assistant
Myrna M. Killey, B.A., Technical Assistant
PUBLICATIONS
Betty M. Lynch, B.Ed., Technical Editor
Carol A. Brandt, B.A. , Technical Editor
Jane E. Busey, B.S., Assistant Technical Editor
Marie L. Martin, Geologic Draftsman
James R. Gilmer, Asst. Geologic Draftsman
Sandra L. Oncken, B.F.A., Asst. Geologic Draftsman
William Dale Farris, Research Associate
Dorothy H. Scoggin, Technical Assistant
Beulah M. Unfer, Technical Assistant
Dorothy Rae Weldon, Technical Assistant
GENERAL SCIENTIFIC INFORMATION
Peggy H. Schroeder, B.A., Research Assistant
Florence J. Partenheimer, Technical Assistant
SPECIAL TECHNICAL SERVICES
Glenn G. Poor, Research Associate (on leave)
Merle Ridgley, Research Associate
David B. Cooley, Technical Assistant
Wayne W. Nofftz, Supervisory Technical Assistant
Donovon M. Watkins, Technical Assistant
James E. Taylor, Automotive Mechanic
Lynn W. Wright, Technical Assistant
FINANCIAL OFFICE
Velda A. Millard," in charge
Marjorie J. Hatch, Clerk IV
Virginia C. Smith, B.S., Account Clerk
Pauline Mitchell, Account Clerk
CLERICAL SERVICES
Jane C. Washburn, Clerk-Stenographer III
Nancy J. Hansen, Clerk- Stenographer II
Hazel V. Orr, Clerk- Stenographer II
Mary K. Rosalius, Clerk- Stenographer II
Dorothy M . Spence, Clerk- Stenographer II
Becky L. Dowds, Clerk -Stenographer I
MagdelineE. Hutchison, Clerk- Stenographer I
Edna M. Yeargin, Clerk- Stenographer I
Sharon K. Zindars, Clerk -Stenographer I
Shirley L. Weatherford, Key Punch Operator II
JoAnn L. Lynch, Clerk-Typist II
Pauline F. Tate, Clerk-Typist II
TECHNICAL RECORDS
Berenice Reed, Supervisory Technical Assistant
Miriam Hatch, Technical Assistant
Hester L. Nesmith, B.S., Technical Assistant
LIBRARY
Lieselotte F. Haak, Geological Librarian (on leave)
Ann M. Sokan, M.A. , Acting Geol . librarian
EMERITI
M. M. Leighton, Ph.D., D.Sc, Chief, Emeritus
J. S. Machin, Ph.D., Principal Chemist, Emeritus
O. W. Rees, Ph.D., Prin. Research Chemist, Emeritus
W. H. Voskuil, Ph.D., Prin. Mineral Economist, Emeritus
G. H. Cady, Ph.D., Senior Geologist, Emeritus
A. H. Bell, Ph.D., Geologist, Emeritus
George E. Ekblaw, Ph.D., Geologist, Emeritus
J. E. Lamar, B.S., Geologist, Emeritus
L. D. McVicker, B.S., Chemist, Emeritus
Enid Townley, M.S., Geologist, Emerita
Lester L. Whiting, M.S., Geologist, Emeritus
Juanita Witters, M.S., Physicist, Emerita
B. J. Greenwood, B.S., Mechanical Engineer, Emeritus
RESEARCH AFFILIATES AND CONSULTANTS
Richard C. Anderson, Ph.D., Augustana College
W. F. Bradley, Ph.D., University of Texas
Donald L. Graf, Ph.D., University of Minnesota
Ralph E. Grim, Ph.D., University of Illinois
S. E. Harris, Jr., Ph.D., Southern Illinois University
Lyle D. McGinnis, Ph.D., Northern Illinois University
I. Edgar Odom, Ph.D., Northern Illinois University
T. K. Searight, Ph.D., Illinois State University
Harold R. Wanless, Ph.D., University of Illinois
George W. White, Ph.D. , University of Illinois
Topographic mapping in cooperation with the
United States Geological Survey.
CIRCULAR 441
ILLINOIS STATE GEOLOGICAL SURVEY
URBANA 61801
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