302 BROOKS AND KINDLE PALEOZOIC EOCKS OF UPPER YUKON 



has mapped an area lying southeast of Tagish lake, presents the following 

 succession of Paleozoic rocks : 



Greenstone, magnetite, serpentine, peridotite, and actinolite slates (in part 



Mesozoic ) . 

 Crystalline limestone, probably Cax'boniferous, cherty quartzite, black slate, 



biotite slate, and limestone. 

 Quartzite, bornblende and chloritic schists, and crystalline limestone. 



Of these subdivisions he appears to regard the two middle ones as 

 equivalents of Dawson's Cache Creek series. 



In the hope of obtaining more data on the age of this limestone, Mr 

 Kindle visited the Dawson locality on Windy arm of Tagish lake. A dili- 

 gent search in the limestone yielded, however, only a few fragmentary 

 fossils, on which Doctor Girty reported as follows : 



"The only fossils obtained at this point are the following : Round crinoid 

 stems ; a small simple terebratuloid having much the shape of Dielasma for- 

 mosum Hall, but of a type common to many horizons ; a fragment of a large 

 complanately coiled shell, not showing septa, but probably a nautiloid rather 

 than an ammouoid ; a fragment of a small chambered shell, not showing the 

 suture line, which, as the septa are seen in the weathered section to be folded, 

 is probably an ammonoid. 



"This fauna may be Carboniferous, but the evidence is too imperfect for 

 satisfactory determination. If Carboniferous, the facies is distinctly different 

 from the ordinary Alaskan Carboniferous fauna, which abounds in Productus 

 and other brachiopods and is almost without cephalopods. In view of this 

 fact and the other, that the faunal relations of the Alaskan Carboniferous are 

 much more with the Russian and Asiatic sections than with those of central 

 United States, this fauna contains a certain suggestion of the Artinsh, but 

 this is more of a speculation than an inference." 



It is clear that these scattered facts are not sufficient, in the absence of 

 corroboratory paleontologic evidence, for correlating this Carboniferous 

 limestone with any of the Yukon terrains, though the writers would tenta- 

 tively suggest its equivalency to the Upper Carboniferous. 



In southeastern Alaska the general succession of the Carboniferous 

 rocks is very well known. There is, however, no definite knowledge as to 

 the total thickness of the Carboniferous, owing to the absence of any 

 single continuous section of the entire series. At least 3,000 feet of the 

 Paleozoic rocks are known to belong to the Carboniferous, and more com- 

 plete information abotit the middle portion of the series may double this 

 thickness. The lowest division of the Carboniferous comprises about 

 1,500 feet of dark, cherty, generally thin-bedded limestone, with a Lower 

 Carboniferous fauna. These rocks are well exposed at Freshwater bay, on 



