Page:Oregon Historical Quarterly vol. 6.djvu/175

169 JOURNAL OF A VOYAGE TO N. W. AMERICA. 169 cula & handkerchiefs were filled with mosses and land shells; phrenogamous plants were abundant; the pools along the banks of the river contained plenty of fluviatile crabs ; and the features of the rocks gave me a clear idea of the geological structure of the surrounding country. I may here condense all the geological facts respecting this country I have been able to collect. There are no high mountains within thirty miles of Fort George. The country consists of sloping hills of gradual ascent & regular outline, quite free from the rugged & barren ap- pearance of the primitive formations. From the soft nature of the rocks of the Columbia & from the great size of the river during the summer months, immense quantities of sand are deposited in different situations. From the abundance of these materials the numerous al- luvial islands of the Columbia are deposited & banks & shoals are formed in every part of the river. These islands are some of them two or three miles in extent, & would afford the richest agricultural returns, if they were not annually covered by the waters of the river dur- ing two months of the year. All the mud & sand of the river is not thus deposited; part of it is carried out to the ocean, & by the action of the Westerly winds, which blow three fourths of the year, it is accumulated at the mouth of the river & forms the chief danger of the navigator who visits the Columbia. Point Adams on the South side of the river seams to be entirely an alluvial deposition, formed by the united efforts of the sea & river. On going [to] the north of Cape Dissapointment we find the same causes operating there. The [sea] has undoubtedly made considerable encroachments on the rocks, but this opera- tion must be diminished yearly from the effects of its own efforts. The rocks are worn away & disintegrated & deap & capacious caverns excavated in their sides, but