Historical:Ravinia Sand Member
John C. Frye and H. B. Willman
The Ravinia Sand Member of the Lake Michigan Formation (Willman and Frye, 1970, p. 78) is named for Ravinia, in the southern part of Highland Park, Lake County.
The type exposure is an accessible section of the Lake Michigan beach (W½ 31, 43N-13E).
The Ravinia Member includes only beach sand and is separated from the rest of the formation at the base of the low-water swash zone. Sands occurring offshore are included in the Waukegan Member. The character of the beach sands and adjacent deposits in extreme northeastern Illinois and the history of their development have been described by Hester and Fraser (1973).
It consists of well sorted, largely medium-grained, nearly white beach sand containing local lenses of gravel. It is relatively clean, except for man-made litter and driftwood. Smaller areas of beach sand present along the shores of other natural lakes in Illinois are included in the Ravinia.
HESTER, N. C., and G. S. FRASER, 1973, Sedimentology of a beach ridge complex and its significance in land-use planning: Illinois State Geological Survey Environmental Geology Notes 63, 24 p.
WILLMAN, H. B., and J. C. FRYE, 1970, Pleistocene stratigraphy of Illinois: Illinois State Geological Survey Bulletin 94, 204 p.
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