After travelling this day our customary distance, which was about twenty-five miles, we were compelled to halt at a place where we could find no poles to set up our tents. We were fortunate in finding part of a tree which had drifted down the Platte, and which sufficed to make a fire for the cooking of our supper. An Indian dog, who had made his appearance at the encampment on the preceding day, had followed us thus far, but kept aloof, not allowing us to come within one or two hundred yards of him. On the following morning, six miles from our camp, we arrived at the confluence of the north and south fork of the Platte. We had halted here, and were making preparations to examine the north fork, with a view of crossing it, when we saw two elk plunge into the river a little above us on the same {151} side. Perceiving it was their design to cross the river, we watched them until they arrived on the other side, which they did without swimming. We accordingly chose the same place they had taken, and putting a part of our baggage in a skin canoe, waded across, leading our horses, and arrived safely on the other side; no accident having happened, except the wetting of such of our baggage as was left on the horses. The north fork at its confluence is about eight hundred yards wide, is shoal and rapid like the Platte, and has a sandy bed. We were informed by our guide, who had been repeatedly to its sources, that it rises within the Rocky Mountains, about one hundred and twenty miles north of the sources of the Platte. It is probably the river which was mistaken by Captain Pike for the Yellow-stone, and has been laid down as such on his map, whence the mistake has been copied into several others. It has its source in numerous small streams, which descend from the hill surrounding a circumscribed valley within the mountains, called the Bull-pen. This basin is surrounded by high and rugged mountains, except at the place where the north fork passes into the plains. On each side of this strait, or pass, are high and abrupt rocky promontories, which confine the river to a narrow channel. The diameter of the circumscribed valley, called the Bull-pen, is one day's travel, about twenty miles.[102] The upper branches of the north fork have some timber, mostly cotton-wood and willow, and abound in beaver.[103] [102] North Platte River rises in Laramie County, Colorado, in the high valley called North Park, enclosed by the Park Range and the Medicine Bow Mountains. It flows north to Natrona County, in central Wyoming, and thence turns to the southeast.—ED.