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National Geologic Map Database

Geologic Unit: Tyler

Usage:

Tyler Formation of Amsden Group (MT*)
Tyler Formation (ND*)


Subunits:

(alphabetical): Bear Gulch Member (MT*,ND*), Cameron Creek Member (MT*,ND*), East Buffalo Creek Limestone Member (MT), Stonehouse Canyon Member (MT*,ND*).


Geologic age:

Late Mississippian to Early Pennsylvanian (Chesterian to Morrowan)*


Type section, locality, area and/or origin of name:

Beautifully exposed at east end of Middle Bench, along east flank of Little Snowy Mountains, in T. 12 N., R. 22 E., 1 mi west of post office of Tyler [historical (closed in 1940); approx. Lat. 46 deg. 49 min. 51 sec. N., Long. 108 deg. 52 min. 17 sec. W., Tyler 7.5-min quadrangle], Fergus Co., central MT (Freeman, 1922).
Reference section: from NE/4 SW/4 sec. 25 to SW/4 sec. 36, T. 13 N., R. 19 E., to NE/4 sec. 1, T. 12 N., R. 19 E., Fergus Co., central MT (Maughan and Roberts, 1967).


AAPG geologic province:

Central Montana uplift*
Powder River basin*
Sweetgrass arch*
Williston basin*


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

Asterisk (*) indicates published by U.S. Geological Survey authors.

"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 ([ ]).