National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Bony Falls member
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Michigan basin

Hussey, R.C., 1952, The Middle and Upper Ordovician rocks of Michigan: Michigan Geological Survey Publication, no. 46, 89 p., Completion of report published as part of Michigan Geol. Survey Pub., no. 40 (Geol. Ser., no. 34). Also issued as Michigan Geol. Survey Geol. Ser., no. 39


Pg. 13, 14, 16, 17-22. Bony Falls member of Black River formation. Section at Bony Falls consists of about 40 feet of limestone some of which is argillaceous and some finely crystalline dolomitic; a 2-inch layer of bentonite occurs about middle of section, and this may mark top of Black River. Evidence of subaerial erosion appears at several levels throughout section, and a very obvious disconformity near middle of section may represent a time break of considerable duration. Underlies Chandler Falls member (new) of Trenton formation. Separation of Black River rocks from Trenton above presents difficult problem; rocks of the two formations are commonly distinguished on basis of faunal changes that are not always very significant; deposition was practically continuous at some localities from Black River to Trenton time, and dividing line between the two formations becomes an arbitrary one. Age is Middle Ordovician.
Type locality: at Bony Falls on Escanaba River, in sec. 1, T. 41 N., R. 24 W., Delta Co., northern MI.

Source: US geologic names lexicon (USGS Bull. 1200, p. 429).

For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

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