North Hill Group
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.
Elwood Atherton, Charles Collinson, and Jerry A. Lineback
North Hill Group (Laudon, 1931, p. 344).
Named for the North Hill area of Burlington, Iowa.
The name was introduced for the oldest member of the Hampton Formation, but Laudon later (1935) made the unit a formation. Workman and Gillette (1956) made it a group to include the McCraney Limestone at the base, the Prospect Hill Siltstone, and the Starrs Cave Limestone.
The type section of the North Hill Group is located near the North Hill area of Burlington, Iowa.
The group is conformable on the Hannibal Shale but is overlain unconformably by the Burlington Limestone.
Extent and thickness
These formations (the McCraney Limestone, the Prospect Hill Siltstone, and the Starrs Cave Limestone), extensive in Iowa, are confined in Illinois to a narrow belt east of the Mississippi River in extreme western Illinois (fig. M-9), where they have a maximum thickness of about 110 feet.
Well log characteristics
Age and correlation
Conodonts and other fossils indicate that the North Hill Group correlates with the Chouteau Limestone (Collinson, 1961).
Environments of deposition
COLLINSON, CHARLES, 1961, Kinderhookian Series in the Mississippi Valley, in Northeastern Missouri and west-central Illinois: Kansas Geological Society Guidebook, 26th Annual Field Conference, Missouri Geological Survey Report of Investigations 27, p. 100-109; Illinois State Geological Survey Reprint 1961-U.
LAUDON, L. R., 1931, Stratigraphy of the Kinderhook Series of Iowa: Iowa Geological Survey, v. 35, p. 333-451.
LAUDON, L. R., 1935, Supplemental statement on the Mississippian System in Iowa: Kansas Geological Society 9th Annual Field Conference Guidebook, p. 246-247.
WORKMAN, L. E., and TRACEY GILLETTE, 1956, Subsurface stratigraphy of the Kinderhook Series in Illinois: Illinois State Geological Survey Report of Investigations 189, 46 p.
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