Geol.— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 5 



in part crystalline, and in part metamorphic sediments, that 

 make up the mass of the Blue Mountains in northeastern 

 Oregon. Their limits have not been ascertained, but they 

 appear to flank these mountains upon the west much as they 

 do the Sierra Nevada in California; and here, also, they are 

 in turn overlaid by fresh-water Tertiary deposits and Neo- 

 cene lavas. 



It would appear from what is known of the distribution 

 of the Cretaceous sediments south of the Columbia River, 

 and of the older basement series that in Cretaceous 

 time formed the floor and margin of the sea, that the 

 western coast-line of the Cordilleran continent in early 

 Cretaceous time was roughly determined by the three older 

 mountain groups, — the Sierra Nevada, the Klamath Moun- 

 tains, and the Blue Mountain system in northeastern 

 Oregon. 



It is not yet proved that in later Cretaceous time the sea 

 extended along the whole eastern base of the Klamath 

 group, thus severing them wholly from the mainland, with 

 which they had previously been connected. 



Cretaceous rocks are not definitely known in the coast 

 mountains of northwestern Oregon nor of Washington; yet 

 certain beds are known along the Columbia River opposite 

 Astoria, and in the Coast Ranges southward, that not im- 

 probably belong to this period. In the vicinity of Puget 

 Sound, in British Columbia, and on the adjacent islands, 

 the Cretaceous rocks have a distribution not less important 

 than they have in California. They rest here upon a base- 

 ment of earlier Mesozoic and older rocks, and extend east- 

 ward upon the flanks of the Cordilleran platform. As in 

 Oregon and northern California, these beds are found 

 occupying the chief valleys among a system of mountains 

 composed essentially of pre-Cretaceous rocks. Farther 

 north, on the southern coast of Alaska, Cretaceous beds 

 are reported in the vicinity of Cook's Inlet, Kodiak Island, 

 and on the Alaskan peninsula (Dall, 1895-96). They 

 occur also at Rink Rapids, upon the Arctic border of the 

 continent. 



(2) October 23, 1902. 



