| State | Missouri |
|---|---|
| Name | St. Francois mountains volcanic supergroup |
| Geologic age | Precambrian Y |
| Lithologic constituents |
Major
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic-ash flow)
Minor
Igneous > Volcanic > Felsic-volcanic > Trachyte (Pyroclastic-ash flow)
|
| Comments | The St. Francois Mountains is a region of formerly extentive volcanic terrane comprising several calderas, cauldron subsidence structures, ring intrusions, and resurgent cauldrons. Three calderas are recognized: the Taum Sauk, the Butler Hill, and the Hawn Peak. |
| Stratigraphic units | Includes Taum Sauk Group and Butler Hill Group. |
| References | Howe, W.B. and Koenig, 1961, The Stratigraphic Succession in Missouri: Missouri Geological Survey and Water Resources, Vol XL. 2nd Series. |
| NGMDB product | |
| Counties | Carter - Iron - Madison - Reynolds - Saint Francois - Shannon - Washington - Wayne |