The banks of the river, for a considerable distance, both above and below the falls, have a volcanic character: masses of basaltic rock are piled one upon another; the water makes its way through their broken chasms, boiling through narrow channels, or pitching in beautiful cascades over ridges of basaltic columns.
Whenever he approached Snake River, he found it running through a broad chasm, with steep, perpendicular sides of basaltic rock. After several days' travel across a level plain, he came to a part of the river which filled him with astonishment and admiration.
After encamping at this place all night, Captain Bonneville, at sunrise, descended with his party through a narrow ravine, or rather crevice, in the vast wall of basaltic rock which bordered the river; this being the only mode, for many miles, of getting to the margin of the stream.
Basaltic rocks rise perpendicularly, so that it is impossible to get from the plain to the water, or from the river margin to the plain.
We had left the beach early in the morning, and after an uninterrupted, though at times difficult and dangerous ascent, during which we had never once turned our faces to the sea, we found ourselves, about three hours before sunset, standing on the top of what seemed to be the highest land on the island, an immense overhanging cliff composed of basaltic rocks
, hung round with parasitical plants.