Pilot Knob Felsite of /Butler Hill Group of /St. Francois Mountains Volcanic Supergroup (MO-recognized locally in St. Francois Mountains area)
[Name Butler Hill applied concurrently to two different units in same area; preempted by Butler Hill Granite of Tolman and Robertson (1969); name St. Francois Mountains applied concurrently to two different units in same area; a [supergroup] name combines a geographic name with the term ["supergroup,"] and no lithic designation is included (see ACSN, 1970; NACSN, 1983, 2005, 2021).]
Mesoproterozoic
Typically exposed at Pilot Knob, Iron Co., MO. Origin of name not stated, but probably named from Pilot Knob (Tolman and Robertson, 1969).
Midcontinent region
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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