National Geologic Map Database
Geologic Unit: Rifle Hill
Map showing publication footprint
  • Usage in publication:
    • Rifle Hill Member
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Iowa shelf
    • Wisconsin arch

Sloan, R.E., 1987, Tectonics, biostratigraphy, and lithostratigraphy of the Middle and Late Ordovician of the Upper Mississippi Valley, IN Sloan, R.E., ed., Middle and Late Ordovician lithostratigraphy and biostratigraphy of the Upper Mississippi Valley: Minnesota Geological Survey Report of Investigations, no. 35, p. 7-20.


Rifle Hill Member, upper member of Stewartville Formation of Galena Group (in Minnesota), and Rifle Hill Member, upper member of Wise Lake Formation of Galena Group (in Illinois and Iowa). Replaces Stewartville Member (revised) of Wise Lake Formation in Illinois and Iowa [not adopted by the Iowa Geological Survey]. At type section, is the dolomitic limestone above the corrosion surface of the Sinsinawa Member of Stewartville Formation and below the marker bed at the base of Dubuque Formation; thickness 11.56 m (about 38 feet). Is distinctively orange colored, commonly styolitic; has "swiss-cheese" weathering. Underlies Frankville Member of Dubuque Formation. Present in the Upper Mississippi Valley (Iowa shelf and Wisconsin arch). Contains abundant gastropod MACLURITES, "upper RECEPTACULITES zone," and conodonts. Age is Late Ordovician (Edenian). Report includes correlation chart, cross sections, graphic section.
Type section: Rifle Hill Quarry, in NE/4 NW/4 sec. 35, T. 102 N., R. 12 W., Fillmore Co., southeast MN.

Source: Modified from GNU records (USGS DDS-6; Reston GNULEX, Denver GNULEX).

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

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).