Lost River - Karst Information Portal

County (Gray, Jenkins, and Weidman, 1960,
p 48) and 240 feet (73 meters) in southern
Monroe County (Malott, 1952, p 57). From
well records the group is known to be 150 to
170 feet (46 to 52 meters) thick in parts of
Owen and Putnam Counties, and in other areas
in the subsurface its thickness ranges from 625
to 450 feet (99 to 137 meters) near the outcrop
to a maximum of 650 feet (198 meters) in
Posey County (Pinsak, 1957, pl 1). Oolitic
limestones constitute 22% the Ste. Genevieve
and Paoli limestones as seen in seven cores
equally spaced along the length of outcrop in
southern Indiana lying on the eastern edge of
the Illinois Basin. Similar oolitic limestones are
found in equivalent stratigraphic formations in
Kentucky and Illinois. Isopach mapping and
analysis of 889 crossbedding measurements
in the Illinois Basin indicate that paleoslope
during deposition of these oolitic limestones
was to the southwest, as it was earlier during
deposition of carbonate sands of the Salem
Limestone and later during deposition of most
of the late Paleozoic sands.
The Blue River Group rests conformably
on the Sanders Group and is overlain, generally
conformably but with local disconformity,
by rocks of the West Baden Group. North of
Owen County the Mansfield Formation of
Pennsylvanian age disconformably overlaps
successively older Blue River rocks northward.
The Blue River Group has no exact named
equivalent in neighboring states, but it is
equivalent to the section extending from the
St. Louis Limestone through the Cedar Bluff
Group of Illinois usage (Swann, 1963). It spans
the Valmeyeran–Chesterian boundary as that
boundary is generally recognized. The Blue River
Group includes rocks that at different times
were assigned to units with the now-obsolete
names Mitchell Formation (Limestone, Group,
of Hopkins and Siebenthal, 1897, pp 298–299;
Elrod, 1899, p 259; Ashley and Kindle, 1903, p 73;
Malott, 1919, pp 8–10, and 1921, p 365; Logan,
1926, p 343) and Lower Kaskaskia Limestone
(Kindle, 1896, pp 331–332). The upper
boundary of the Mitchell in these older uses
was as low as the top of the St. Louis Limestone
Stratigraphy and Lithology
(Fired, 1899, p 259) and as high as the top of the
Beaver Bend Limestone (Malott, 1919, 1921;
Logan, 1926). Because of these irregularities in
earlier usage, Cumings (1922, p 507) and Perry
and Smith (1958, p 19) recommended that the
term Mitchell be abandoned, but it remained for
Gray, Jenkins, and Weidman (1960) to describe
and name the Blue River Group as an appropriate
replacement term.
Ste. Genevieve Limestone – The Ste.
Genevieve Limestone, like the other Middle
Mississippian formations, thickens from 45 to
220 feet to the south and west and its outcrop
belt becomes narrower to the north. Like the
Harrodsburg and Salem, the Ste. Genevieve
can be divided into three members. The lower
member is the Fredonia, often called the
Fredonia oolite for the characteristic lithology. It
is light gray to gray, dense, medium grained, and
generally thick bedded or massive. Large lensoid
masses of nearly white oolite may be interbedded
with dense, gray, thin-bedded limestone with
sand-sized fossil debris (Shaver, et al, 1986, pp
128–130.
About 10 to 37 feet above the St. Louis–Ste.
Genevieve contact is the prominent marker bed
known as the Lost River Chert. The Lost River is
a siliceous limestone to bedded chert up to 5 feet
in thickness and is characterized by a high content
of fossils, especially bryozoans and brachiopods.
It is very prominent in the Lost River region but
thins north of Lawrence County. It is a resistant
unit and frequently supports waterfalls in caves
as well as in surface streams.
The Spar Mountain (Rosiclare) Member, the
middle member of the Ste. Genevieve Limestone,
is probably not exactly equivalent to the type
Rosiclare of southern Illinois which is a true
quartz calcareous sandstone averaging 30 feet
thick. In Indiana the unit commonly consists of a
few inches to a few feet (up to 40 feet) of coarsegrained,
thin-bedded, silty or sandy limestone
containing some shale. The Spar Mountain
also consists of sandy, oolitic limestone; shale;
or thin argillaceous sandstone and, in places,
contains limestone conglomerate and breccia. In
the Owen County vicinity (Cataract Falls), the
Spar Mountain is commonly a medium-grained