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University of California. 



[Vol. 3. 



the exception of a slight very recent subsidence, the coast line 

 seems to have been rising intermittently for a considerable 

 period. At any rate, the river has not been materially shortened 

 during the down-cutting from the 850-foot terrace. It is out 

 of the question that the river could have descended 1,200 feet 

 in sixty miles and yet eroded such a broad valley. Taking into 

 consideration the present high grade of the stream and the past 

 lower grade, it is probable that, although the bed-rock floor of 

 the highest terrace is but 725 feet above the river at Orleans, 

 it has been uplifted about 1,000 feet. This elevation has been 

 intermittent and, so far as the Orleans Basin is concerned, not 

 differential in character until after the completion of the 

 deposits of the seventy-foot terrace. One of the principal uplifts 

 is represented by the interval between the 475-foot and the 120- 

 foot terraces, and if it extended over a broad territory it may 

 have been concerned in the formation of the glaciers of the 

 Intermediate stage. The last uplift, to which the Modern earion 

 is due, was perhaps of equal importance. 



Perhaps I should state that I do not expect the same relative 

 importance between the different uplifts to obtain throughout 

 the Klamath region. It is my impression that in general, and 

 especially farther east than Orleans, the last uplift greatly pre- 

 ponderated over the others in amount of elevation. It was of a 

 decidedly differential character, decreasing to almost nothing 

 at the present coast-line. 



Changes of Climate. — When I entered upon this study I 

 hoped to gain an intimation of variation in the climate by a com- 

 parison of the size of the channels of the different terraces, but 

 I have not been able to get any decisive evidence on this point. 

 The various channels appear to be similar in size to the present. 

 If there is any difference it is that the channels of the Upper 

 Group are smaller than the present channel. The size of the 

 channel is conditioned upon the grade as well as the volume of 

 water; therefore, considering the original low-grade condition 

 of the Upper channels, if they are smaller, or at least no larger 

 than the present channel, they indicate a smaller run-off (less 

 precipitation) than the present. 



The second line of evidence which I hoped would yield an 



