FOSSIL HUNTING IN MONTANA AND WYOMING 



By CHARLES W. GILMORE 



Curator, Division of Vertebrate Paleontology, U. S. National Museum 



Exploration of the Miocene and Oligocene formations of south- 

 western Montana was planned for the season of 193 1, in an effort 

 to fill existing gaps in the fossil vertehrate collections of the National 

 Museum. 



Leaving Washington on June 1, I first visited Trinidad, Colo., to 

 investigate a discovery brought to our attention by George Heap of 

 that city. A week spent here resulted in the recovery of a large marine 

 turtle from the Pierre formation. Turtles are rarely found in this 

 formation, and since this large swimming turtle (Arch clou) was 

 previously unrepresented in our collection it is a welcome addition. 

 Following this, I joined my party at Belgrade, Mont., on the eve- 

 ning of June 11, where camp had been established and work begun 

 by George F. Sternberg and M. V. Walker, engaged as field assis- 

 tants prior to my leaving Washington. A week's work on their part 

 in the Miocene exposures paralleling the Madison River for some 

 miles along its lower course had produced meager results and it re- 

 quired but a short time to convince me that to continue exploration 

 in the Madison formation of this region was but a waste of time and 

 effort. Collecting conditions were rendered difficult by the vegeta- 

 tion which covered the exposed slopes and the fact that bands of 

 sheep had recently grazed over the area. Some desirable material 

 new to the collections was found, but not sufficient to justify the 

 expense and labor involved. 



Unlike many fossil fields where a party of three men may spend 

 an entire season in one locality without covering all of the ground, 

 the Tertiary of this part of Montana consists for the most part of 

 small, scattered patches of exposures. Consequently from June 13 

 until the latter part of the month we were almost constantly on the 

 move. Under the guidance of C. A. Kinsey, of Belgrade, a corre- 

 spondent of the Museum who is familiar with the fossil beds of this 

 part of Montana, we visited the famous Pipestone Creek locality near 

 Pipestone Springs. The formation here, named for the creek, is of 

 Ohgocene age and consists of a few outcropping exposures along the 



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