Historical:Sauk Sequence
Chronostratigraphy: Paleozoic Erathem >>Cambrian System >>Ordovician System
Allostratigraphy: Sauk Sequence
Author
T. C. Buschbach
Name Origin
The Sauk Sequence (Sloss et al., 1949, p. 111) is named for Sauk County, Wisconsin.
Definition
The Sauk Sequence consists of all strata between the unconformity on the top of the Precambrian rocks and the sub-Tippecanoe unconformity at the base of the St. Peter Sandstone or Everton Formation. In Illinois it therefore includes all strata of Cambrian and Canadian (lower Ordovician) age (fig. 14).
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Description
Local channeling at the base of some of the sandstones may have been mainly submarine and no unconformities are recognized within the sequence. The sequence was uplifted by gentle warping and minor faulting and was deeply eroded before deposition of the overlying Tippecanoe Sequence (Atherton,1971).
References
ATHERTON, ELWOOD, 1971, Tectonic development of the Eastern Interior Region of the United States: Illinois State Geological Survey Illinois Petroleum 96, p. 29-43.
SLOSS, L. L., W. C. KRUMBEIN, and E. C. DAPPLES, 1949, Integrated facies analysis, in Sedimentary facies in geologic history: Geological Society of America Memoir 39, p. 91-123.
SWANN, D. H., and H. B. WILLMAN, 1961, Megagroups in Illinois: American Association of Petroleum Geologists Bulletin, v. 45, p. 471-483; Illinois State Geological Survey Reprint 1961-N.
ISGS Codes
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