Whitney’s Geology of California. 365 
the north and south sides of Mt. Shasta, and also at numerous 
points along the eastern side of the Sacramento valley for nearly 
a hundred miles south of Pitt river. In places these volcanic 
rocks have an immense thickness; in fact, the lofty Mt. Shasta 
and Lassen’s peak are but enormous piles of these voleanic 
products. 
These two prominent peaks are the grandest objects of north- 
ern California. Both were ascended and measured barometri- 
oe by members of the survey, the former in 1862, the latter 
in 18638. 
hasta is a very regular cone, rising to an altitude of 
mit, and emenations of steam, hot water, sulphur, and gases are 
how its only symptoms of activity. : 
i ia about eighty miles southeast of this, on the 
a is less regular in outline, and it rises from a much higher 
ase than Mt. Shasta. On its broad flanks are a large number 
along its entire length, too numerous for even an enumeration 
in this place. : \ 
he immense mass of the higher Sierras, lying between the 
~ latitudes of 35° and 39°, was left unnoticed in our consideration 
