698 PROCEEDINGS OP THE OTTAWA MEETING 



and stratigraphic relations are often undetermined. Though these metamor- 

 phic beds have been subdivided into many formations, many of these are ill 

 defined, and much more detailed evidence • will be required before a definite 

 statement as regards the succession can be made. Some of the lower members 

 of this great complex have yielded Ordovician and Silurian fossils, while in 

 some of the upper beds Devonian fossils have been found. In the Yukon basin 

 and in the panhandle there appears to be an unconformity near the base of 

 the Devonian, below which the rocks are much more highly metamorphosed. 

 The older and more crystalline sediments are probably Silurian, Ordovician, 

 Cambrian, or possibly pre-Cambrian. The metamorphosed elastics of south- 

 eastern Alaska include Devonian and Carboniferous, and elsewhere in the 

 province Devonian and Carboniferous terranes have been found. 



Triassic beds have thus far been recognized only in the Copper River basin 

 and in southwestern Alaska, while the Jurassic occurs in this district and also 

 at cape Lisburne, in northern Alaska. The lower Cretaceous is widely dis- 

 tributed and includes the youngest beds known to have suffered any consider- 

 able metamorphism. It appears that the unconformity separating the upper 

 and lower Cretaceous horizons was of considerable extent. The upper Cre- 

 taceous occurs in the Yukon basin, in southwestern and southeastern Alaska, 

 as well as north of the Rockies. 



Of the Tertiary horizons the Eocene coal-bearing beds are the only ones 

 which have been found widely distributed, and these occupy no considerable 

 areas. Miocene and Pliocene beds appear to have relatively small development 

 The Pleistocene is represented throughout the province by gravels, sands, and 

 silts, and in the regions which have been occupied by ice by various forms of 

 glacial deposits. 



Correlation Table, 



On the table I have indicated the stratigraphic succession in four of the best 

 known districts and suggested certain correlations between them. 



In southeastern Alaska the basal member consists of phyllites and crystal- 

 line limestones, in part at least of Silurian age. These are succeeded by 

 crystalline limestones and slates of Middle Devonian age. The next horizon 

 is a chert and limestone series, carrying lower Carboniferous fauna and rest- 

 ing unconformably on the older rocks. These are succeeded by a complex of 

 phyllites and greenstones, with some limestones, in part at least of Permian 

 age. A heavy conglomerate series, resting unconformably on the Paleozoic 

 rocks, represents the oldest Mesozoic of this province, and is probably 

 Cretaceous. These are unconformably overlaid by a soft sandstone and shale 

 series, in part of upper Cretaceous, in part of Eocene age. 



The extensive basalt flows have been provisionally assigned to the Miocene, 

 while the Pleistocene is represented by silts, sands, and gravels, as well as by 

 glacial drift. 



Highly metamorphosed schists and limestones form the oldest sediments of 

 the Copper River region, and are of pre-Devonian age. These are uncon- 

 formably succeeded by a massive conglomerate and slate series, associated 

 with volcanic rocks which have been provisionally referred to the Devonian. 

 The Carboniferous is represented by a lower member, made up of heavy 

 crystalline limestone, and an upper consisting of many thousand feet of lime- 

 stones, shales, and volcanics. These are overlaid by a volcanic and limestone 



