russell.] BIG, MIDDLE, AND EAST BUTTES. 35 
expanding and becoming indefinite at their lower extremities and 
clearly indicating the amount of erosion that has occurred since the 
encircling basalt was poured out. Equally apparent is the fact that 
the mountain was deeply seamed by erosion before the basalt flowed 
about it. The land surface on which the old volcano was built and 
the streams of acid lava which it may have sent out are buried from 
sight by the basalt, and no inequalities of the present surface suggest 
hills or hollows beneath the deep covering of black lava. These con- 
trasts in topography coincide with even more sharply defined differ- 
ences in the rocks. The mountain is composed mainly of nearly white 
rhyolitic lava, which presents many variations from compact, banded, 
and spherulitic layers to light pumice and black glass or obsidian. 
The encircling basalt is black, with but a single neighboring area at 
the north base of the white butte, where a remnant of a small basaltic 
cinder cone reveals a dash of dark red. The ancient steptoe is built 
of highly acid lava and the surrounding plain is composed of basic- 
lava. 
An exception to the statement that there are no exposures of the 
land surface on which the ancient rhyolitic mountain was built may 
perhaps occur about 5 miles to the east of its base, where a group 
of hills, clothed in part with juniper trees, rise to a height of about 
300 feet above the recent basalt that intervenes between the two. An 
examination of this group of hills was cut short by the coming of 
darkness, but the occurrence of obsidian and pumice in what seemed 
to be a remnant of a lapilli cone suggested that a small volcano, similar 
to the greater one which formed Big Butte, may there be represented. 
Big Butte, like the surrounding plain, is grass covered, and the 
numerous deer trails, on which the imprint of the foot of a wolf or a 
wildcat may occasionally be noticed, show that it is a favorite feeding 
ground for big game. Elk resort there in winter and bears are com- 
mon visitors. An arrow point, of obsidian, picked up on the summit 
of the mountain, suggested that this was formerly an Indian hunting- 
ground. Just before my visit it had rained, and on the plain about 
3 miles to the south of the butte there was a small water pocket from 
which trails radiate in various directions, showing that year after year 
the same depression had been occupied by water and for a long time 
had been resorted to by wild animals. Besides grasses and flowers, 
the mountain is covered in certain favored places on its northern slopes 
with a young and thrifty growth of pines, firs, and juniper, and much 
of the summit portion is occupied by a dead forest of coniferous trees, 
many of them 30 to 40 feet high, which were killed by tire about eight 
or ten years ago. Over the greater portion of the burnt area, which 
includes nearly the entire mountain, no young trees have sprouted. 
There is so little moisture that the forest will never be renewed. It 
