Such may have been the fate of the early inhabitants of the Pacific continent: certainly it would not be surprising, if the immense climatic and geographical changes which then took place would produce that result. Or it may be that but a scanty remnant lived on, absorbed by more vigorous, though less highly cultivated stocks of the same people, whose homes had been on the main-land of Asia—and the remnant left along the Pacific coast must have lived on under vastly different circumstance. The interior of North America was largely a dreary expanse of ice and snow down to the 39th parallel of latitude. It is quite true, this great glacier did not reach the Pacific Slope; but it must have exerted a powerful influence on the climate: and the evidence points, that the Sierra Nevada were occupied by local glaciers which reached down into the fertile expanse of the plains.
This was certainly a far different climate, and a far different country, than that which sustained a vegetation of a tropical growth. It may well be that the people should, as a result of their changed conditions, have deteriorated in culture; or, at any rate, their progress toward civilization may have been stopped, and many thousands of years may have passed with no perceptible improvement. It may be objected, that man will improve under any state of existence, give him time enough. This is, doubtless, in the main true. But a race may early reach its limit of culture; in which case, as a race, it will not improve: we may do much with the individual, but nothing, or but very little, for the race.
In these considerations which have been advanced we may find some reason for the early appearance of Neolithic man, as well as the fact that he advanced no farther in culture. But whether man first arrived in California in Pliocene times or not, he continued to inhabit the land to the present day. He would, however, be exposed to assault after assault from invading tribes. We do not wish to examine the question of the origin of the native Americans. It is held, by the best authorities, that at least a portion of them came from Asia, using the Kurile Islands as a stepping stone. Reaching the main-land of America, and passing down the coast, they would, sooner or later, reach the Valley of the Columbia—which has been characterized as the most extraordinary region on the face of the earth in the variety and amount of subsistence it afforded to tribes destitute of a knowledge of agriculture. At certain seasons of the year the rivers are crowded with fish, and they are then caught with the greatest ease. As a mixture of forest and prairie, the country is an excellent one for game. A species of bread-root grew on the prairies; and, in the Summer, there was a profusion of berries. To these advantages must be added that of a mild and equable climate.28