Lithostratigraphy: Ottawa Limestone Megagroup >>Platteville Group >>Plattin Subgroup >>Grand Detour Formation >>Victory Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
Allostratigraphy: Tippecanoe Sequence
H. B. Willman and T. C. Buschbach
The Victory Member of the Grand Detour Formation (Templeton and Willman, 1963, p. 86) is named for Mt. Victory School, Calhoun County, 4.5 miles north of the type section.
The type section of the Victory Member is located in a quarry north of West Point Landing (SE NE SE 19, 7N-2W), where it is 5.5 feet thick.
Extent and Thickness
The Victory Member is commonly only a foot or less thick in the northern outcrop area but is 3 feet thick in La Salle County, and in the southern outcrop area it ranges from 3.5 feet near St. Louis to 7 feet at Cape Girardeau.
The Victory Member is a distinctive, white to light gray lithographic limestone containing calcite flecks that give it the "bird's-eye" appearance typical of limestones equivalent to Platteville limestones in other regions. Many of the calcite flecks are fillings of corallites of Tetradium. The Victory Member is massive to thick bedded and locally contains a little chert. In northern Illinois it locally grades to light gray, white-weathering dolomite, and it is not as distinctive as it is in the southern area, where it is the most easily identified member of the Platteville Group. Although generally absent north of Illinois, beds similar to the Victory occur in Kentucky, Tennessee, and New York.
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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