Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
T. C. Buschbach
Sauk Sequence (Sloss et al., 1949, p. 111).
Named for Sauk County, Wisconsin.
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). 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).
Extent and thickness
Well log characteristics
Age and correlation
Environments of deposition
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.
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