108 THE MOUNTAINS OF CALIFOENIA 



the way up to those that are new born, lying bare 

 and meadowless among the highest peaks. 



A few small lakes unfortunately situated are ex 

 tinguished suddenly by a single swoop of an ava 

 lanche, carrying down immense numbers of trees, 

 together with the soil they were growing upon. 

 Others are obliterated by land-slips, earthquake 

 taluses, etc., but these lake-deaths compared with 

 those resulting from the deliberate and incessant 

 deposition of sediments, may be termed accidental. 

 Their fate is like that of trees struck by lightning. 



The lake-line is of course still rising, its present 

 elevation being about 8000 feet above sea-level; 

 somewhat higher than this toward the southern 

 extremity of the range, lower toward the northern, 

 on account of the difference in time of the with 

 drawal of the glaciers, due to difference in climate. 

 Specimens occur here and there considerably below 

 this limit, in basins specially protected from in- 

 washing detritus, or exceptional in size. These, 

 however, are not sufficiently numerous to make 

 any marked irregularity in the line. The highest 

 I have yet found lies at an elevation of about 

 12,000 feet, in a glacier womb, at the foot of one 

 of the highest of the summit peaks, a few miles to 

 the north of Mount Bitter. The basins of perhaps 

 twenty-five or thirty are still in process of forma 

 tion beneath the few lingering glaciers, but by the 

 time they are born, an equal or greater number will 

 probably have died. Since the beginning of the close 

 of the ice-period the whole number in the range has 

 perhaps never been greater than at present. 



A rough approximation to the average duration 



