Clark: July 10, 1806

Thursday, July 10th, 1806. Last night was very cold, and this morning everything was white with frost and the grass stiff frozen. I had some water exposed in a basin in which the ice was 3/4 of an inch thick this morning. I had all the canoes put into the water and every article which was intended to be sent down put on board, and the horses collected and packed with what few articles I intend taking with me to the River Rochejhone (Yellowstone). After breakfast we all set out at the same time and proceeded on down Jeffersons River on the east side through Service Valley and Rattlesnake Mountain and into that beautiful and extensive valley, open and fertile, which we call the Beaverhead Valley, which is the Indian name in their language Har na Hap pap Chah, from the number of those animals in it and a point of land resembling the head of one.

This valley extends from the Rattlesnake Mountain down Jeffersons River as low as Fraziers Creek above the Big Horn Mountain, and is from 12 to 30 miles in width and ____ miles on a direct line in length. Jeffersons River, in passing through this valley, receives McNeals Creek, Track Creek, Philanthropy River, Wisdom River, Fields River, and Fraziers Creek, each throwing in a considerable quantity of water and having innumerable beaver and otter on them. The bushes in their low bottoms are the resort for great numbers of deer, and in the higher parts of the valley we see antelope scattered feeding. I saw also on the sides of the rock in Rattlesnake Mountain 15 bighorn animals. Those animals feed on the grass which grows on the sides of the mountain and in the narrow bottoms on the watercourses near the steep sides of the mountains, on which they can make their escape from the pursuit of wolves, bears, etc.

At meridian I halted to let the horses graze, having come 15 miles. I ordered them to land. Sergt. Ordway informed me that the party with him had come on very well, and he thought the canoes could go as fast as the horses, etc., as the river now becomes wider and not so shallow. I determined to put all the baggage, etc., which I intend taking with me to the River Rochejhone in the canoes and proceed on down with them myself to the Three Forks, or Madisons and Galletens Rivers, leaving the horses to be taken down by Sergt. Pryor and 6 of the men of the party to accompany me to the River Rochejhone, and directed Sergt. Pryor to proceed on moderately and if possible camp with us every night.

After dinner I had my baggage put on board and set out, and proceeded on tolerably well to the head of the 3000 Mile Island, on which we had camped on the 11th of August last. The canoes passed six of my encampments ascending. Opposite this island I camped on the east side. The mosquitoes were troublesome all day and until one hour after sunset, when it became cool and they disappeared. In passing down in the course of this day we saw great numbers of beaver lying on the shores in the sun. Wild young geese and ducks are common in this river. We killed two young geese this evening. I saw several large rattlesnakes in passing the Rattlesnake Mountain; they were fierce.