. Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean . mulation of soil on the surface and the dense growth of largetrees which it supported. Lassens butte is evidently a volcanic cone, and one whose fires have not been long extin-guished. Its summit is distinctly crateriform, as will be seen from the accompanying cut, andis capped with perpetual snow, and has an altitude of about 9,000 feet. Below the snow linefor 1,000 feet the mountain is bare of vegetation, and covered with piles of lava
. Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean . mulation of soil on the surface and the dense growth of largetrees which it supported. Lassens butte is evidently a volcanic cone, and one whose fires have not been long extin-guished. Its summit is distinctly crateriform, as will be seen from the accompanying cut, andis capped with perpetual snow, and has an altitude of about 9,000 feet. Below the snow linefor 1,000 feet the mountain is bare of vegetation, and covered with piles of lava, or slopes ofashes. GEOLOGY—LASSENS BUTTE—CANOE CREEK. 31 The geology of all this region bears the record of intense and recent volcanic action. Thesurface crossed before reaching the summit of the pass was covered with blocks of scoriaceous trap,pumice, trachyte, or porphyry. The prevailing rock at the highest part of our route is a friablefelspathic lava, which readily disintegrates, forming a white sand, which reflects the sunalmost like snow. This rock is lying in rough and ragged masses, in many places bare ofvegetation, and of recent lassens butte, fbom the north. The open space about the base of Lassens butte is doubtless due to the fires which, from timeto time, sweep through these pine forests, yet a large area in its vicinity is overspread withvolcanic products, evidently of so recent date that it seems not improbable that it has been ina state of activity since many of the pines which are growing on its base began their existence. This accumulation of modern volcanic matter completely conceals all underlying rocks, andgives an uninteresting monotony to the geology of the surrounding region. On Canoe creek, a tributary of Pit river, we found the first of the Sage plains, which formso constant a feature of the central desert. They here present arid surfaces of but limited extent,bounded by cliffs, or ledges of trap, and covered with a light volcanic soil,
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