454 OSCAR H. HERS HEY 



2. That the intermediate glacial stage probably corresponds 

 to the lowan. 



3. That the deposits supposed to represent the earliest glacial 

 stage yet recognized are at least zs old as the lUinoian and per- 

 haps as old as the Kansan glaciation. 



CLIMATIC CONDITIONS DURING THE SEVERAL GLACIAL STAGES. 



The comparative abundance of serpentine in the earliest 

 supposed drift of the Salmon River valley and its rarity as 

 superglacial material in later drifts raises a question as to the 

 cause of this difference. A given glacier in each stage occupied 

 the same valley and would be expected to yield drift of like 

 constitution. 



Linked with this phenomenon there is another. I know that 

 the earlier glaciers ran farther than the later, and I have acquired 

 the idea that they were of a radically dii^erent character, par- 

 ticularly that they were much thinner at a given distance from 

 the end than were the glaciers of the last stage. This may be 

 wholly imaginary, but I usually do not acquire such ideas with- 

 out there being some basis for them ; in the field I have now 

 studied the earlier drift in three distinct areas (the Union Creek, 

 Coffee Creek, and Salmon River valleys) and each independently 

 has made a similar impression on me. This is after eliminating 

 all differences due to the profound erosion. of the earlier drift. 



The only satisfactory explanation of the phenomena that has 

 come to light is that as between the earlier and later glacial 

 stages there was a radical difference in the character of the 

 climate. The earlier drift was formed under low altitude conditio7is 

 and the later drift under high altitude conditions. 



On a recent trip from the coast at Eureka to this region, made 

 shortly after a severe snow-storm, I had the opportunity of 

 observing some meteorological phenomena having a direct bear- 

 ing on the question at issue. On Redwood Mountain near the 

 coast I found at an altitude of 3,600 feet, a depth of six feet of 

 snow. As I advanced inland, the line of, say, two feet depth of 

 snow gradually rose, and when I reached the region under dis- 

 cussion, I found that there had been not more than two and a 



