Port Clarence Limestone, Alaska. 339 



of these lies between the Don and California Rivers, and the 

 other extends northward from Brooks Mountain. (See fig. 1.) 

 Both of these have been correlated, without,* however, any con- 

 clusive evidence of their identity, with the slate series lying west 

 of the Port Clarence limestone. Knopf's contribution to the 

 question of the order of succession of these slates and the Port 

 Clarence limestone, is the statement that they are connected 

 by a transition zone in which the " limestones of the Port 

 Clarence formation merge imperceptibly into members of the 

 slates,"f and that their present order of superposition in the 

 vicinity of Brooks Mountain represents their original order. 

 A small collection of fossils presented to the writer by Mr. 

 Peter Esch of Nome, Alaska, is of interest in this connection. 

 Mr. Esch states that these fossils were collected by him on the 

 southeast slope of Brooks Mountain between 1,000 and 2,000 

 feet above sea level. Dr. T. W. Stanton has furnished the 

 following report on this collection : 



" The fossils (No. 5654) include the following species : Dao- 

 nella sp. related to D. lornelli Wissmann, Ceratites {G-ymnoto- 

 eeras) sp. 



These are characteristic Triassic fossils and probably came 

 from the Middle Triassic. The collection is interesting from 

 the fact that it affords the first evidence of the existence of 

 Triassic rocks in that part of Alaska.'^ 



If these fossils were found at Brooks Mountain as the col- 

 lector reports, the black slates in the vicinity of Brooks Moun- 

 tain are, in part at least, of Triassic age and Triassic sediments 

 are present in the Seward Peninsula as at Cape Thompson, 125 

 miles to the northward, where the writer has found a Triassic 

 fauna following the Carboniferous limestones.§ 



From the type region of the Port Clarence in the York 

 Mountains its correlation has been extended to various lime- 

 stone masses elsewhere in the Seward Peninsula on the 

 basis either of poorly preserved fossils or of stratigraphic 

 methods. In most cases the limestone areas outside the York 

 Mountain district are altered by metamorphism to such an 

 extent as to afford no paleontologic evidence which will either 

 confirm or disprove the correlation which has been made. In 

 one of these metamorphosed areas in the southern part of the 

 Peninsula, Mr. P. S. Smith | has begun the work of resolving 



* Bull. U. S. Geol. Survey, No. 328, 1908. 



t Bull. U. S. Geol. Survey, No. 358, p. 13, 1908. 



\ Letter to the writer November 18, 1908. 



§ Kindle, E. M., The section at Cape Thompson, Alaska, this Journal, vol. 

 xxviii, pp. 527-528, 1909. 



| Geology and mineral resources of the Solomon and Cassadapaga quad- 

 rangles, Seward Peninsula, Alaska : Bull. U. S. Geol. Survey No. 433, p. 54, 

 1910. 



