Historical:Sankoty Sand Member
H. B. Willman and John C. Frye
The Sankoty Sand was named by Horberg (formally in 1950a; in abstract 1946a) for its presence in wells in the Sankoty water-well field along the Illinois River on the north side of Peoria, Peoria County. The Sankoty Sand has been described by Horberg (1950a, 1953), MacClintock and Willman (1959), McComas (1968), and Walker, Bergstrom, and Walton (1965).
The type section is in a well in NW SE Sec. 15, T. 9 N., R. 8 E., Peoria County.
The Sankoty Sand is classified here as a member of the Banner Formation. The Sankoty Sand is overlain by tills of the Banner Formation, except where the till was eroded, which is common, and in places it is overlain by Illinoian or Wisconsinan formations. It rests directly on bedrock formations.
Extent and thickness
The Sankoty Sand occurs in the deepest part of the Ancient Mississippi Valley and adjacent parts of the major tributaries. It averages about 100 feet thick, but locally may be as much as 300 feet thick.
It consists largely of medium- and coarse-grained sand and is distinguished from other outwash sands by an abundance of pink quartz grains, many of which are highly polished. It contains little silt and clay. Some beds are pebbly, but gravel is not common.
Age and correlation
Horberg (1953) considered the Sankoty Sand to be of Nebraskan age, but it is not known to have a soil on it where it is overlain by Kansan age till, and it is more likely pro-Kansan outwash. It probably is present almost continuously in the deep part of the Ancient Mississippi Valley throughout Illinois, and it may extend to the Gulf Coast. The basal Pleistocene sand, called the Natchez Formation, at Natchez, Mississippi, contains polished pink sand grains like those in the Sankoty.
HORBERG, C. L., 1946a, Pleistocene deposits below the Wisconsin drift in Illinois [abs.]: Geological Society of America Bulletin, volume 57, p. 1204.
HORBERG, C. L., 1950a, Bedrock topography of Illinois: Illinois State Geological Survey Bulletin 73, 111 p.
HORBERG, C. L., 1953, Pleistocene deposits below the Wisconsin drift in northeastern Illinois: Illinois State Geological Survey Report of Investigations 165, 61 p.
MacCLINTOCK, PAUL, and H. B. WILLMAN, 1959, Geology of Buda Quadrangle, Illinois: Illinois State Geological Survey Circular 275, 29 p.
McCOMAS, M. R., 1968, Geology related to land use in the Hennepin region: Illinois State Geological Survey Circular 422, 24 p.
WALKER, W. H., R. E. BERGSTROM, and W. C. WALTON, 1965, Preliminary report on the ground-water resources of the Havana region in west-central Illinois: Illinois State Geological Survey and Illinois State Water Survey Cooperative Ground-Water Report 3, 61 p.
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