6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 92 



Beartooth Mountains. — The recent work of the Princeton Uni- 

 versity group studying the geology of the Beartooth region has shown 

 the presence of Middle Cambrian on the northwestern quadrant of 

 the Beartooth Mountains. On the eastern and southern sides of this 

 uplift only the Southern Rocky Mountain Upper Cambrian series is 

 present, but west of a gap where Cambrian is lacking, the presence 

 of northern Middle Cambrian apparently determines the southeastern 

 extent of the geosynclinal seas washing the margins of the more 

 stable lands which prevented their continuation southward through 

 Wyoming or the Southern Rockies. 



All four new localities mentioned lie within the Rocky Mountains 

 proper, and in every respect their strata resemble those previously 

 determined by Walcott's studies ; consequently they serve merely to 

 close the gap between the previously known Cambrian areas in the 

 southern part of the Northern Rockies. In other wqrds, these dis- 

 coveries were to be expected as long as definite evidence was not at 

 hand that the known Middle Cambrian seaways had detoured around 

 this supposedly barren Beltian area. From our knowledge we may, 

 therefore, infer that a thin, probably discontinuous sheet of Middle 

 Cambrian once covered some of this Beltian area, but no evidence 

 exists pointing to the extension of younger Cambrian beds across the 

 area. Naturally, thin beds, lying on top of great masses folded and 

 faulted into the high ranges such as exist here at present, would suffer 

 severely from erosion, with the result that only patches of Cambrian 

 are left here and there in the bottoms of synclines. Nevertheless, it 

 is the opinion of all who have studied the region that the Middle 

 Cambrian sheet never extended all the way across the gap. 



DISCOVERIES WEST OF THE ROCKY MOUNTAINS 



In contrast to the four finds described, another group located in 

 northeastern Washington contribute not so much toward closing the 

 gap, but have a much greater significance, since they occur west of the 

 Rocky Mountains in the strike of the Selkirk and Purcell systems. 



Metaline Falls.— K^cenWy Washington State geologists searched 

 patiently the hitherto supposedly unf ossilif erous metamorphosed rocks 

 in the eastern part of their State and were rewarded by finding fossils 

 which prove the presence of Paleozoic strata as was previously sus- 

 pected. Last winter, Mr. W. G. Bennett, a student of Washington 

 State College, found a shale containing good Middle Cambrian fos- 

 sils at Metaline Falls on the Pend Oreille or Clark Fork River in the 

 northeastern corner of the State, a few miles south of the international 



