268 STANTON 



amount of erosion of the underlying beds before the conglomerate 

 was deposited. Taking as a datum plane a fossiliferous band in the 

 Parkman sandstone it is seen that the beds between it and the base of 

 the conglomerate vary in thickness from about 1300 feet to more than 

 3000 feet in a distance of two miles along the strike. 



In a small collection of fossil plants from a white, friable sandstone 

 about 2000 feet above the Parkman and nearly the same distance 

 below the Kingsbury in sec. 6, T. 49 N., R. 82 W., Doctor Knowlton 

 has identified 5 Fort Union species which are listed in his paper. 

 What relation this horizon bears to the Piney farther north where 

 dinosaur bones were found is still an open question. The most impor- 

 tant collections, however, are from finer strata interbedded with the 

 Kingsbury conglomerate about 600 feet above its base. From this 

 part of the section the collections include a considerable list of Fort 

 Union plants, a few land and fresh-water invertebrates most of which 

 are undescribed but seem to be related to Wind River and Wasatch 

 rather than to earlier forms, and a part of a small mammal jaw with 

 the teeth in place. Concerning this jaw Mr. J. W. Gidley reports 

 that it is 



identical with a genus and species occurring in the 'Silberling quarry" 

 in Silberling's Fort Union No. 2. Apparently the genus and species 

 are new, so that at present about all that can be said of the Gale speci- 

 men is that it is closely allied to Tricentetes, a genus found in the 

 Torrejon of New Mexico. The close correspondence of the specimen 

 to like portions found in the bed of the Silberling .quarry, leaves 

 little doubt that the horizons are equivalent. 



All the evidence both paleontologic and stratigraphic tends to prove 

 that the unconformity at the base of the Kingsbury conglomerate is 

 well up in the Fort Union. Since it has been proved to hold this 

 high position the assertion has been made that the unconformity is 

 purely local and relatively unimportant because the conglomerate 

 extends for only 30 or 40 miles along the strike. That it is unimpor- 

 tant and local may be true, but such an assumption should not be 

 made until it has been compared with other observed unconformities 

 which also may or may not be local. 



Bighorn Basin. — Except in the extreme northern part it has been 

 difficult to recognize in Bighorn Basin the same subdixisions between 



