PALEOZOIC EOCKS, FICKETT SERIES. 71 



In referring the series to the Lower Carboniferous, however, it should be borne 

 in mind that the fossils were nearly all found in the northern part of the field, where 

 they have apparently come from near the lower part of the section, and since the 

 series is possibly 8,000 to 10,000 feet in thickness, it may extend not only into 

 Upper Carboniferous but possibly into Lower Mesozoic. 



Correlation. — Carboniferous fossils have been collected by Spurr° and Collier 

 on the Yukon above Circle, by Mendenhall and the writer in the northern part of 

 the Copper Basin, and by Dall in southeastern Alaska, on Kuiu Island, but these all 

 seem to be Upper or Permo-Carboniferous, and therefore afford no ground for close 

 correlation of the rock occurring there with those of the section here considered. 



Independent of paleontologic evidence, on purely lithologic grounds, some of the 

 gray schist, sandstone, and limestone beds of the series toward the northern part 

 were associated by the writer in the field with the West Fork series of Chandlar 

 River, 6 which is regarded as possibly the source of some of the Paleozoic fossils 

 found in the river gravels below that point, and which has been relegated by 

 Doctor Girty to Carboniferous or Devonian. 



Carboniferous forms are reported to have been collected on Captain Beechey's 

 voyage/' 1825-1828, on the northwest coast between Cape Beaufort and Cape Thomp- 

 son (see PI. V). More recently, in the Cape Lisburne region, plant remains have 

 been collected by Mr. Dumars which have been identified by Mr. David White as a 

 small species of Lepidode?idron, related to L. chemungense, and a small form of 

 Stigmaria ficoides, indicative of Carboniferous age. This denotes at least the 

 presence of Carboniferous rocks in the Cape Lisburne region, which, on future 

 investigation, may be correlated with the Fickett series, and suggests that the rocks 

 of the two regions may be continuous in the mountains lying between them, as the 

 Devonian is supposed to be. (See p. 66.) 



In fact, if topographic criteria be taken into account — namely, the continuation 

 of the mountains eastward beyond the international boundary — with what has been 

 said of the occurrence of the Lisburne formation, it may here be briefly stated, in 

 concluding the subject of Paleozoic rocks, that the present exploration, together 

 with the evidence previously collected in the region to the east and that to the 

 west, toward Cape Lisburne, seems to indicate beyond question the extension of 

 a well-developed belt of Paleozoic rocks across northern Alaska, coinciding with 

 the trend of the Rocky Mountains from the one hundred and thirty-fifth meridian, 

 near the Mackenzie, to the one hundred and sixty-sixth, at Cape Lisburne, a distance 

 of nearly 1,000 miles. 



aSpurr, J. E., Geology of the Yukon gold district, Alaska: Eighteenth Ann. Rept. U. S. Geol. Survey, pt. 3, 1898. 

 bSehrader, F. C, Reconnaissance along the Chandlar and Koyukuk rivers, Alaska: Twenty-first Ann. Rept. U. S. Geol. 

 Survey, pt. 2, 1900. 



"Voyage of Captain Beechey to the Pacific and Behring's Straits, London, 1836, pp. 378-405. 



