128 C. W. TOMLINSON 



UPPER CAMBRIAN AND EARLY ORDOVICIAN 



4. (Known at Blacksmith Fork only.) 640 feet. Includes the following types, 

 in descending order: 



Thin-bedded, light-gray, finely crystalline dolomite; in the upper part 

 interbedded with olive shales and very fossiliferous. 206 feet. (Beekman- 

 town.) 



Fossiliferous, dark blue-gray or blue-black, very finely crystalline dolo- 

 mite with much black chert throughout, and a 30-foot bed of black chert at 

 the base. 156 feet. (Beekmantown.) 



Brownish-gray to bluish-gray, finely to coarsely crystalline dolomite in 

 i-foot to 5-foot beds. 278 feet. 



3. Mostly thin-bedded to shaly, bluish-gray to brownish-gray, finely crystalline 

 dolomite and dolomitic shale, with many layers of flat-pebble limestone con- 

 glomerate. In part fossiliferous. M.T., 800 feet, Blacksmith Fork (lower 

 190 feet, Upper Cambrian, placed in the St. Charles formation by Walcott; 

 remainder Ordovician). This member is represented throughout northern 

 and western Wyoming and southwestern Montana. 



2. (Not differentiated except at Blacksmith Fork.) Finely to coarsely crystal- 

 line, gray dolomite, mostly thin-bedded, weak; in part oolitic. 349 feet, 

 Blacksmith Fork. 



1. Very massive, cliff -making, coarsely crystalline white dolomite, interbedded 

 near the top and bottom with minor beds of thinner-bedded gray dolomite. 

 M.T., 412 feet, Livingston Peak. 



o. Mostly thin-bedded, white to light- and dark-gray, finely to coarsely crystal- 

 line dolomite, locally with much sandstone in lower part, and with inter- 

 bedded flat-pebble limestone conglomerate. In part fossiliferous. Lower 

 (barren) half called Middle Cambrian by Walcott at Blacksmith Fork 

 (upper part of the Nounan formation). M.T., 654 feet, Blacksmith Fork. 



PALEONTOLOGICAL COLLECTIONS: ASSEMBLED LISTS 



DEVONIAN 



Members 5-1 1: 



Actinostroma sp. Antler peak, Livingston Peak. 



Alveolites goldfussi Billings. Livingston Peak. 



Anplexus cf. hamiltoniae Hall. Antler Peak. 



Blothrophyllum{ ?) cf . cinctutum Davis. Antler Peak. 



Zaphrentis{ ?) sp. Livingston Peak. 



Atrypa missouriensis Miller. Livingston Peak. 



Bryozoa. Antler Peak, Livingston Peak (2 sp.). 

 Member 3 : 



Atrypa missouriensis Miller (fragmentary). Teton River. 

 Member 2: 



Unidentifiable brachiopod and gastropod fragments. Teton River. 



Leperditia sp. Livingston Peak, Teton River (2 sp.). 



