8 BULLETIN 169, UNITED STATES NATIONAL MUSEUM 



(see resume and references in Thorn and Dobbin, 1924) aside from the 

 Crazy Mountain area and briefer mention of mammal discoveries 

 elsewhere. 



The earliest geological work in the particular area here under dis- 

 cussion appears to be that of W. H. Weed. In 1893 he mentioned the 

 presence of about 4,000 feet of Fort Union sediments overlying his 

 Livingston formation east of the Crazy Mountains. In the Livingston 

 (Weed, 1894) and Little Belt Mountains (Weed, 1899) fohos, he in- 

 cluded the extreme western part of this area and referred to the 

 presence of Fort Union here but mapped it all as Livingston. In an 

 article on the Fort Union (Weed, 1896) he also discussed the Fort 

 Union area in a general way and gave a section of part of these and of 

 lower beds along Lebo Creek. 



The first more detailed consideration of this area and the first ade- 

 quate reference to its more important northeastern part was by Earl 

 Douglass. In 1900 he worked here, principally in the Cretaceous but 

 also in the Fort Union, where he collected leaves and invertebrates. 

 In 1901 a Princeton University expedition was sent out under Dr. 

 M. S. Farr, and Douglass accompanied this party and also continued 

 work after they had left. The Princeton party traversed the Fort 

 Union exposures, but most of theu* work of that season was in the 

 Cretaceous. In August 1901, Douglass found the first mammals in 

 this field, and the first ever discovered in the Fort Union, at two 

 locahties (5 and 6 of the lists given on a later page) near the northern 

 end of Bear Butte. Although fragmentary and few, these sufficed to 

 show the equivalence of these beds to the Torrejon of New Mexico 

 (Douglass, 1902a). Douglass soon pubhshed detailed descriptions of 

 the mammals and a discussion of the geology of the whole area (Doug- 

 lass, 1902b). The Princeton party was also accompanied by Albert 

 Silberling, then a boy of 16, who was destined to play the major role 

 in the development of this field. 



Princeton field parties, also under Dr. Farr and accompanied by 

 Silberling, revisited the area in 1902 and 1903, and they then examined 

 the Fort Union in more detail and found fossil mammals at a number 

 of scattered localities and at widely different levels, from near the base 

 of the formation to about 4,350 feet above the base and from the 

 northeastern part of the field to the vicinity of Cayuse Butte, near the 

 western margin of the principal mammal-bearing area. The fossils 

 collected and observations made in 1902 and 1903 have never been 

 published. 



In 1905 Douglass made a long reconnaissance through Montana, 

 and in the course of this he went northward from Bigtimber to Cayuse 

 (or Melville) Butte. He noted the presence of the Fort Union over 

 much of this traverse but did not add significantly to exact knowledge 

 of the field. Apparently he had not been informed of the unpubfished 



