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Sierra Club Bulletin 



feet apart. In the great upper Tuolumne Basin, which held an 

 ice-field embracing 140 square miles, the earlier and later ice- 

 floods differed only 200 feet in level, as is to be inferred from 

 the two ice-lines on Ragged Peak. And on the Cathedral 

 Range, which was in large measure the generator of this im- 

 mense ice-field, being the great hedge behind which the wind- 

 blown snows accumulated, the difference was least of all. From 

 Cathedral Peak eastward to Mount Lyell it lessened by degrees 

 until at length it became insignificant. 



The figures are but a very few out of many scores deter- 

 mined by the writer on both ice-lines. Indeed, the total num- 

 ber of determinations made was large enough to enable him to 

 construct a contour map of each ice surface. These contour 

 maps, he is happy to say, have furnished excellent proof of the 

 mutual concordance and consistency of the data. 



The group of pinnacled mountains, it will be clear from the 

 foregoing, stands in a region where the two ice-floods reached 

 substantially the same height. Most of the work of paring 

 away the sides of the pinnacles and crests was done by the 

 earlier ice-flood, which was the one of greater duration, bvit 

 the later ice-flood undoubtedly did much to accentuate the ef- 

 fect produced by the first. It is a significant fact that farther 

 down on the Sierra flank, where the ice-lines diverge widely in 

 altitude, and where the fluctuations in level of each of the 

 floods no doubt were of considerable amplitude, no attenuated 

 pinnacles or crests rising abruptly from ice-rounded moun- 

 tains are to be found. 



In Greenland, which is one of the few parts of the earth 

 even now under the dominion of the ice, an Eskimo word is 

 commonly used fo designate those barren rocky summits that 

 protrude here and there above the rapidly descending glaciers 

 forming the fringes of the vast and otherwise continual glacial 

 mantle. That word is nunatak. Physiographers throughout 

 the world have adopted it as a technical term for rocky sum- 

 mits rising above surrounding ice-sheets and glaciers. The 

 pinnacles and crests of the Cathedral Range might, therefore, 

 be referred to as former nunataks. But the appropriateness 

 and desirability of so styling them are, in the writer's opinion, 

 open to question. 



