74 GLACIAL AND SUEFACE GEOLOGY OF THE PACIFIC COAST. 



from the north towards the south, or of any condition of things similar to that 

 wliich must have existed in the Eastern States during the diluvial epoch. 



" On examining the published records of explorers in the central portion 

 of the Continent, it will be noticed that there is strong reason to believe that 

 the absence of the Northern Drift formation is not peculiar to the States 

 along the Pacific Coast ; but that the whole region west of the Eocky Moun- 

 tains is also destitute of any indications of a detrital formation moved over 

 the surface in one direction by any gi-eat general cause. Judging from our 

 present stock of evidence, I am inclined to draw the line which limits the 

 Northern Drift formation on the south and west approximately from the 

 mouth of the Ohio to the head-waters of the Saskatchewan River." 



The above-quoted communication in regard to the character of the drift 

 deposits on the Pacific Coast has been the subject of repeated severe criti- 

 cisms in various scientific journals at home and in Europe. The subject 

 is an interesting one as bearing directly on a question of much interest, 

 namely, whether the so-called Glacial epoch was of a general, or only of a 

 local character. It is true, however, that tliis question has not now the 

 importance which it had when the above-quoted communication was made 

 to the California Academy. Since that time it has been clearly established, 

 by extended investigations made in Europe and Asia, that the idea that 

 the phenomena of the drift are due to a general North Polar ice-cap is 

 entirely unsupported by facts, as will be more fully explained further on. 

 Nevertheless, the conditions of the Glacial and Northern Drift epochs in 

 North America are so complicated, that everything which can throw light 

 on the various forms and stages of their development is worthy of a careful 

 setting forth. 



As far as California and the mass of the Rocky Mountains south of the 

 immediate vicinity of the United States northern boundary line are con- 

 cerned, the facts are so clear that there can be no dispute, and need be no 

 discussion, about them. Enough has already been said in the preceding 

 pages on this point, and there is no occa.sion to alter anything stated in the 

 first of the paragraphs quoted above. 



In regard to the former glaciation of Nevada and Oregon, included in the 

 second paragraph, little needs to be added. The condition of things in 

 Nevada has already been set forth, in connection with the other portions of 

 the Great Basin. Nor is there occasion to dwell long on Oregon. That State 

 has been sufficiently examined, both by the writer and by Mr. Gabb, to justify 



