A Resource Inventory of Selected Sites Adjacent to the
White Clay Fault in Southwest South Dakota
Lilly Jones, James Sanovia, Hannan LaGarry
Department of Math and Science, Oglala Lakota College
Introduction
The Niobrara Chalk
A geologic and paleontologic resource inventory for two
selected outcrops adjacent to each other in the region of
the White Clay Fault on the Pine Ridge Indian Reservation,
South Dakota, was begun in the summer of 2012.
The Niobrara Chalk formed over the study area 87-82
million years ago when this region was covered by the
Western Interior Seaway (Hattin, 1982; Everhart, 2001).
The selected outcrops are both on the upside of the fault.
The southern outcrop is Late Cretaceous Niobrara Formation
while the northern outcrop is Eocene-Oligocene White River
Group ; a difference of about 50 million years.
Two structural units are recognized: the Fort Hays
Limestone Member and the Smoky Hill Chalk Member. The
type locality is located in Knox County, Nebraska. The
Niobrara Formation underlies the marine Pierre Shale.
(Hattin, 1982).
This resource inventory represents one of a series of steps
being taken by students and faculty at Oglala Lakota College
to catalogue and preserve the resources of the Pine Ridge
Indian Reservation.
The outcrop at the study site consists of the Smoky Hill
Member of the Niobrara Chalk unconformably underlying
Peanut Peak Member of the Chadron Formation of the
White River Group.
An erosional unconformity is indicated by the lack of
approximately 2200 feet (670 m) of Pierre Shale and
Chamberlain Pass Formation of the White River Group.
Geologic Setting
This map is a work in
progress of the study
area. Areas outlined in
orange are Niobrara
Formation outcrops.
Areas outlined in red are
White River Group
outcrops. The image
area is 12 mi.
There is evidence of thrust faulting in a portion of the
outcrop where approximately one meter of breccia lies
between adjacent layers of Niobrara chalk.
Numerous fossils were found, particularly in the faulted
portion of the outcrop, where non-articulated remains
ranging in age from the Cretaceous through the
Pleistocene can be found lying together on the surface in
talus piles along the base of the outcrop.
Fauna List
Cretaceous:
Cretoxyrhina mantelli
Volviceramus grandis
Platyceramus platinus
Volviceramus grandis
Ammonites
Enigmatic tubular structures
Marine reptile remains
(likely Mosasaur or Tylosaurus)
Scattered fish remains (scales,
vertebrae),including Xiphactinus.
Xiphactinus
Recommendations for Management
The White River Group is an accumulation of sediments
consisting of tuffaceous mudstones and siltstones with lesser
amounts of fluvial sandstone, lacustrine limestones and
gypsum that formed over parts of South Dakota, Nebraska,
and Wyoming. (Darton 1899; Schultz and Stout 1955; Clark
and others 1967; Harksen and Macdonald 1969; Swinehart
and others,1985).
Per the Sensitivity Criteria developed by LaGarry and Hunt (1992) the
Niobrara chalk section should be considered both sensitive and rare
as it contains frequent fossils from more than two taxa and grouped
fossils.
The White River Group consists of the Chamberlain Pass,
Chadron and Brule Formations. The Chadron Formation was
formed by a fluvial depositional system and consists of
overbank sequences topped by pedogenically-modified
paleosols. The Chadron Formation contains poorly
consolidated conglomerates at its base.
The White River Group outcrop selected for this inventory
consists of two members of the Chadron Formation: the
Peanut Peak Member overlain by the Big Cottonwood Creek
Member. A calcrete horizon separates these two members as
shown in the photographs below.
Tufa and large tufa tubes were found at this site as
indicated in the photograph at the bottom left. These may
indicate the presence of a hot spring and are often
associated with faults.
Interestingly, the Eocene-Oligocene White River Group is
lower in the landscape than the adjacent Cretaceous
Niobrara outcrop. The lowest part of the landscape consists
of quaternary alluvial residuum.
Volviceramus grandis
Peanut Peak member overlying Niobrara chalk
Cretoxyrhina mantelli
The White River Group
Niobrara chalk outcrop
Peanut Peak member, Niobrara chalk, breccia
Calcrete horizon
Platyceramus platinus
Eocene-Oligocene:
Brontothere
Turtle remains
Insect burrows
Pleistocene :
Mammoth tusks
Coprolites with bone fragments
Erosional pattern of Niobrara chalk
Mosasaur
Thrust fault in foreground; erosional unconformity in background
Ammonite
White River Group outcrop
Faulting at the site has exposed fossils from the Cretaceous through
the Pleistocene. This is rather unusual and increases the rarity of this
location. Even more intriguing, the presence of small Mosasaur,
mammoth, Xiphactinus, Brontothere and shark fossils indicates that
there may be larger remains buried at these sites that should be
salvaged and placed in repository due to their rarity and our
responsibility to protect sensitive resources.
Most of the fossils are lying on the surface where anyone might pick
them up. We might also expect this site to change from year to year
and possibly even from season to season due to the extreme weather
and frequency of fires in the area.
It would be in the best interests of the Oglala Lakota tribe to allow
the materials here to be collected and placed in the resource
repository at Oglala Lakota College. These fossils tell the story from
the time when this area was a vast, shallow, inland sea and the
numbers and types of fossils here represent nearly a complete fauna
of the Cretaceous Western Interior Seaway.
Works Cited
Clark, J., J.R. Beerbower, and K.K. Kietzke. "Oligocene Sedimentation, Stratigraphy,
Paleoecology, and Paleoclimatology in the Big Badlands of South Dakota." Fieldiana Geology
Memoirs 5 (1967). Print.
Darton, N.H. “Prelimanary Report on the geology and water resources of Nebraska west of
the one hundred and third meridian.” United States Geological Survey Nineteenth Annual
Report. (1899): pt 4 719-814. Print.
Everhart, M. J., 2001. Revisions to the biostratigraphy of the Mosasauridae (Squamata) in the
Smoky Hill Chalk Member of the Niobrara Chalk (Late Cretaceous) of Kansas. Kansas Acad.
Sci. Trans 104(1-2):56-75.
Harksen, J.C. and MacDonald, J.R. “Type Sections for the Chadron and Brule Formations of
the White River Oligocene in the Big Badlands of South Dakota.” South Dakota Geological
Survey Report of Investigations 99. (1969). Print.
Hattin, Donald E. “Stratigraphy and depositional environment of Smoky Hill Chalk Member,
Niobrara Chalk (Upper Cretaceous) of the type area, western Kansas.” Kansas Geological Survey,
University of Kansas. (1982). Print
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National Grassland (Sherrill Hills, Story, Story NE, Montrose, Orella, Wolf Butte, Five Points,
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Larson, Edwin E., and Emmett Evanoff. "Tephrostratigraphy and Source of the Tuffs of the
White River Sequence." Geological Society of America Special Paper 325 (1998). Print.
Schultz, C.B. and Stout, T.M.”Classification of Oligocene sediments of Nebraska.” Bulletin of
the Nebraska State Museum. (1955): v 4 17-52. Print.
Swinehart, J.B. , Souders, V.L., Deraw, H.M., and Diffendal, R.F., Jr. “Cenozoic paleography
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Paleontologist and Mineralogists. (1985): 209-229. Print.
Terry, Jr., Dennis O., and James E. Evans. "Pedogenesis and Paleoclimatic Implications of the
Chamberlain Pass Formation, Basal White River Group, Badlands of South Dakota."
Palaeogeography, Palaeoclimatology, Palaeoecology 110 (1994): 197-215. Print.
Terry, Jr., Dennis O., Hannan E. LaGarry, and W. Brantly Wells. "The White River Group
Revisited: Vertebrate Trackways/ Ecosystems, and Lithostratigraphic Revision, Redefinition
and Redescription." Geologic Field Trips in Nebraska and Adjacent Parts of Kansas and South
Dakota 10th ser. (1995): 43-58. Print.
Terry, Jr., Dennis O. "Lithostratigraphic Revision and Correlation of the Lower Part of the
White River Group: South Dakota to Nebraska." Geological Society of America Special Paper
325 (1998). Print.
Terry, Jr., Dennis O., John A. Chamberlain, Philip W. Stoffer, Paula Messina, and Patricia A.
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Acknowledgements
I would like to thank the South Dakota Space Grant Consortium, the Louis Stokes
All-Nations Minority Participation program, Oglala Lakota College, the Oglala
Lakota Tribe, NSF-TCUP and NSF-OSPEEC for making this project possible.
Brontothere
Fragments of mammoth tusk
Talus pile of non-articulated fossils
Talus pile at base of faulted section of Niobrara outcrop
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Thrust fault consisting of approximately 1 m of breccia
Tufa tubes
Exploded skull