Historical:Loughridge Sandstone Member
H. B. Willman and T. C. Buschbach
The Loughridge Sandstone Member of the Glenwood Formation (Templeton and Willman, 1963, p. 51), the upper sandstone member, is named for Loughridge School, which is 5 miles northwest of the type section.
The type section of the Loughridge Sandstone Member is located in a ravine 4 miles north of Grand Detour, Ogle County (N1/2 NW NE NE 25, 23N-9E), where it is 9.8 feet thick.
Extent and Thickness
The Loughridge Sandstone Member is differentiated only in the area where the Daysville Dolomite is present. The Loughridge is commonly less than 10 feet thick in the outcrop area but is 22 feet thick in a well at Dixon.
The Loughridge Sandstone Member has the typical Glenwood texture. It merges westward and northward with the upper part of the Nokomis Sandstone Member and southward in subsurface with the Starved Rock Sandstone Member of the St. Peter Sandstone.
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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