Little Studies in the Yosemite Valley. 



9 



the fact that the Little Yosemite is much frequented 

 and in former days was inhabited by Indians, as the 

 round holes in which they ground their acorns, near 

 by, amply attest. 



Again, the assumption seems legitimate that the frag- 

 ments were in an advanced state of disintegration, and 

 broke down and crumbled on the way. Much of the 

 debris that litters the valley floor to-day is in just such 

 a crumbly state. It has lain exposed so long to strong 

 diurnal and seasonal temperature changes that the in- 

 dividual crystals in the granite, each expanding and 

 contracting with a coefficient of expansion peculiar to 

 the mineral composing it — feldspar, quartz, mica or 

 hornblende, — have gradually worked loose and are 

 ready to part company. Those readers who have 

 mountaineered in the Sierras may have had the ex- 

 perience of picking up a rock that would break 

 in the hand and run like sand through the fingers. 

 This suggests an explanation for the forking of the 

 stripes. A decomposing fragment, after having ad- 

 vanced some distance, would break in two. From then 

 on there would be a double trail. Later, each of the 

 pieces would divide, and the trail would split again. 

 Some fragments broke down by degrees into an ag- 

 gregate of half-loose crystals, and their trails widened 

 out progressively. The end in each case came no 

 doubt, when there was nothing left but a little heap 

 of rock grains which the melting waters of springtime 

 carried off with a rush. 



There are several other features of the striped rock 

 floor of the Little Yosemite Valley that demand 

 elucidation, and it is the writer's hope that this article 

 may cause them to receive attention during the excur- 

 sion planned for the coming summer. 



