Geology, &c. of the country west of the Rocky Mountains. 7 
Hood. ‘Two days of severe travelling, with only water at night, 
and some rose and thorn berries for food, brought us down onto a 
prairie extending without apparent limit before us. After travelling 
on this two more days, without even berries, bemg somewhat dubi- 
ous as to the proper route on account of the crossing Indian paths, 
we met with some natives from whom we obtained food. ‘The day 
following, we reached Fort Wallawalla, which is situated at the mouth 
of a creek of the same name, nine miles below the mouth of Lewis 
river. 
We had now reached Terra cognita, a place inhabited by some 
half a dozen white men. Here we parted from our faithful horses, 
some of which had accompanied us from Missouri, while others were 
purchased of Indians, who possess them in great numbers; we next 
hired a boat and guide, and embarked on the Columbia. Qn this 
part of the river, and for a long distance below, there is only drift 
timber, the country being sandy and gravelly, and as you descend, 
there may be seen on one,-often on both shores, the “‘ High black 
rocks,’ mentioned by Lewis and Clarke, presenting pentagonal col- 
umns of from one to five or six feet in diameter, composed of blocks 
of a slightly concave form, set into each other, till they are raised to 
a great heicht. 
At the Great Falls commences scattering timber, which at the 
Cascades, the last rapids before you reach tide water, becomes a 
dense forest, although there are extensive prairies, still lower down. 
Flere the country is crossed by another range of mountains sim- 
ilar to the Blue: mountains, crossed before reaching Wallawalla, 
and here resting on pudding stone. We now experienced the 
first rain, in any quantity, since we left the Forks of the Platte, five 
months before. Descending the river about forty miles, through 
a low country, we reach Fort Vancouver, the principal depét of the 
Hudson Bay Co., the west side of the mountains, situated on the 
north side of the river, one hundred miles from the ocean and,six 
above the mouth of the Wallamette. The country, for many miles 
about Vancouver, is uninterrupted by mountains, and is mostly wood- 
ed. Still, there are many extensive prairies of great fertility, espe- 
cially along nigh the river. Some of these however, are subject to 
be flooded by the freshets which occur in June, when the river rises 
to a great height. 
As you descend the river to within forty miles of the ocean, you 
again meet mountains similar to those at the cascades, in places un- 
