J. LeConte—Ancient Glaciers of the Sierras. 541 
Now the forms produced by erosion depend partly upon the 
kind of rock, and partly upon ‘the kind of erosion. The forms 
determined by water are different from those determined by ‘ce. 
Standing in the middle of the San Joaquin plains, on a clear 
day, the crests of the Sierras are seen Fi i 
the contrast between the two; the sharp saw-like, teeth-like 
outline of the former, and the rounded outlines of the latter. 
So 
duce forms like fig. 1, while ice in the form of glaciers and eternal 
_ Snow tends to the reverse forms of fig. 2. I know not how general 
these distinctions may be, but certainly the Coast range of this 
State is characterized by rounded summits and ridges, and deep 
"2 i i i slate of the summits. The 
tendancy pr cousecrarae ona ie Toa oni a necessary cooperating 
pon esa but the sharp peaks and spires about Cathedral peak are all 
Am, Jour. Sc1.—Tarrp — Vou. V. No 29.—May, 1873. 
