Lithostratigraphy: Ottawa Limestone Megagroup >>Platteville Group >>Pecatonica Formation >>Chana Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
Allostratigraphy: Tippecanoe Sequence
H. B. Willman and T. C. Buschbach
The Chana Member of the Pecatonica Formation (Templeton and Willman, 1963, p. 76) is named for Chana, Ogle County, 9 miles east of the type section.
The type section of the Chana Member is located in a ravine (W 1/2 SE SE NE 24, 23N-9E) where it is 6.2 feet thick.
Extent and Thickness
In the northern outcrop area the Chana Member is commonly less than 5 feet thick, but it reaches 20 feet in southern Illinois.
In the northern area the Chana Member is largely brown, thick-bedded, vuggy, pure dolomite that contains disseminated sand grains and, in places, thin beds of sandstone of the St. Peter texture. The basal part commonly has slightly argillaceous or shaly beds and phosphatic pebbles. In southern Illinois it is largely pure, thick-bedded limestone.
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
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