Strawbridge Member
Lithostratigraphy: Ottawa Limestone Megagroup >>Platteville Group >>Plattin Subgroup >>Quimbys Mill Formation >>Strawbridge Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
Allostratigraphy: Tippecanoe Sequence
Primary source
Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
Contributing author(s)
H. B. Willman and T. C. Buschbach
Name
Original description
The Strawbridge Member of the Quimbys Mill Formation (Templeton and Willman, 1963, p. 92).
Derivation
Named for Strawbridge, Lafayette County, Wisconsin, 3 miles southwest of the type section.
Other names
History/background
Type section
Type location
The type section of the Strawbridge Member is located in the same type section as Quimbys Mill (a small quarry near Etna, Lafayette County, Wisconsin (SE SE 11, 1N-1E)) where it is 7.8 feet thick.
Type author(s)
Type status
Reference section
Reference location
Reference author(s)
Reference status
Stratigraphic relationships
The Strawbridge Member is at the top of the Quimbys Mill Formation.
Extent and thickness
The Strawbridge Member is about 7 feet thick in the northern outcrop area in Illinois and 10-15 feet thick in the southern outcrop area.
Lithology
The Strawbridge Member is similar in lithology to the Shullsburg Member but is less argillaceous, generally thicker bedded, and has fewer and thinner shale partings. It is partly cherty, especially at the top, in northern Illinois.
Core(s)
Photograph(s)
Contacts
Well log characteristics
Fossils
The Strawbridge Member contains numerous fucoids, which are scarce in the older members of the formation and much smaller than those in the underlying Nachusa Formation.
Age and correlation
Environments of deposition
Economic importance
Remarks
References
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
ISGS Codes
| Stratigraphic Code | Geo Unit Designation |
|---|---|