On the west the limit of the range, at least north of about latitude 41°, up to the end of the first decade of the nineteenth century seems to have been the Rocky Mountains. Lewis and Clark, on their great journey of 1804-06, make no mention of the buffalo on the Pacific side of the mountains, hence it is probable that few had crossed there at that time. This would imply that it was the advance of civilisation which impelled the buffalo in numbers finally to seek passes over the Backbone and spread across the upper valley of Green River, of Bear River, and of the Columbia. The possibility always remains that there may have been other causes at work, perhaps climatic, to induce or assist this movement, and it is also possible that the animal may have crossed earlier, and have temporarily refrained from migrating in that direction, perchance on account of extra deep snow or some such natural interference, although the usual snow did not prevent their crossing in dead of winter. Escalante's party in 1776 found abundant signs of buffalo on White River, near the Green, and killed one there. They named a canyon Arroyo del Cibolo because of the many buffalo trails in it. But the modern Pai Utes apparently had no knowledge of this animal, so that if it ever was found in any numbers in southern Utah, the period of occupation must have been remote. Dr. Coues believed that it ranged at one time in Arizona, though he could not recall the ground for this belief, simply remembering that it appeared to him sufficient at the time. The only indication that I know of, of the former presence of the buffalo in southern Utah is a rock picture found on the walls of Kanab Canyon (see page 37), some eight miles north of latitude 37° and about two west of longitude 112° 30´. This drawing would suggest that some natives captured a buffalo not far from the spot, though it might have been the record of a hunt at some other point. Buffalo would not have been likely to cross the vast depths of the Grand Canyon to the southward, hence they could have arrived at this place easily only by way of the Sevier River, the Escalante Desert, or by turning the western end of the Grand Canyon. At Gunnison on Sevier River a buffalo skull was found in a canyon ten feet below the surface. It is more probable that they would come from the north, yet if they did not cross the mountains there till 1810, a new difficulty is met with, for the present Pai Utes seem not to have made any rock pictures. These were done by the pottery-making, house-building Amerinds, who, as far as can be determined, had vanished from the region long before 1810. [Illustration: Picture of Buffalo on Cliff Wall, Southern Utah. Pecked Drawing Copied by B. L. Young.]