Clark: June 20, 1805

June 20th, Thursday 1805. A cloudy morning, with a hard wind all night and this morning. I directed stakes to be cut to stick up in the prairie to show the way for the party to transport the baggage, etc. We set out early on the portage. Soon after we set out it began to rain and continued a short time. We proceeded on through a tolerably level plain, and found the hollow of a deep ravine to obstruct our route, as it could not be passed with canoes and baggage for some distance above the place we struck it. I examined it for some time, and finding it late, determined to strike the river and take its course and distance to camp, which I accordingly did. The wind was hard from the S.W., a fair afternoon. The river on both sides is cut with ravines, some of which pass through steep cliffs into the river. The country above the falls and up the Medison (Medicine) River is level, with low banks. A chain of mountains lies to the west, some parts of which, particularly those to the N.W. and S.W., are covered with snow and appear very high. I saw a rattlesnake in an open plain 2 miles from any creek or wood. When I arrived at camp, I found all well with great quantities of meat. The canoes Capt. Lewis (Capt. Lewis) had carried up the creek 1 mile to a good place to ascend the bank, and taken up.

Not having seen the Snake Indians, or knowing in fact whether to count on their friendship or hostility, we have considered our party sufficiently small, and therefore have concluded not to dispatch a canoe with a part of our men to St. Louis as we had intended early in the spring. We fear also that such a measure might discourage those who would in such case remain, and might possibly hazard the fate of the expedition. We have never hinted to anyone of the party that we had such a scheme in contemplation, and all appear to have perfectly made up their minds to succeed in the expedition or perish in the attempt. We all believe that we are about to enter on the most perilous and difficult part of our voyage, yet I see no one complaining; all appear ready to meet those difficulties which await us with resolution and becoming fortitude.

We had a heavy dew this morning. The clouds near those mountains rise suddenly and discharge their contents partially on the neighboring plains; the same cloud discharges hail alone in one part, hail and rain in another, and rain only in a third, all within the space of a few miles; and on the mountains to the south and S.E. of us, sometimes snow. At present there is no snow on those mountains; that which covered them a few days ago has all disappeared. The mountains to the N.W. and west of us are still entirely covered, are white, and glitter with the reflection of the sun.

I do not believe that the clouds that prevail at this season of the year reach the summits of those lofty mountains; and if they do, the probability is that they deposit snow only, for there has been no perceptible diminution of the snow which they contain since we first saw them. I have thought it probable that these mountains might have derived their appellation of Shining Mountains from their glittering appearance when the sun shines in certain directions on the snow which covers them.

During the time of my being on the plains and above the falls, I, as also all my party, repeatedly heard a noise which proceeded from a direction a little to the north of west, as loud and resembling precisely the discharge of a piece of ordnance of 6 pounds at the distance of 5 or 6 miles. I was informed of it several times by the men, J. Fields particularly, before I paid any attention to it, thinking it was thunder, most probably, which they had mistaken. At length, walking in the plains yesterday near the most extreme S.E. bend of the river above the falls, I heard this noise very distinctly. It was perfectly calm and clear, and not a cloud to be seen. I halted and listened attentively about two hours, during which time I heard two other discharges, and took the direction of the sound with my pocket compass, which was as nearly west from me as I could estimate from the sound. I have no doubt that if I had leisure I could find from whence it issued. I have thought it probable that it might be caused by running water in some of the caverns of those immense mountains, on the principle of the blowing caverns; but in such case the sounds would be periodical and regular, which is not the case with this, being sometimes heard once only and at other times several discharges in quick succession. It is heard also at different times of the day and night. I am at a great loss to account for this phenomenon. I well recollect hearing the Minitarees (Minitarees) say that those Rocky Mountains make a great noise, but they could not tell me the cause, neither could they inform me of any remarkable substance or situation in these mountains which would authorize a conjecture of a probable cause of this noise. It is probable that the large river just above those Great Falls, which heads in the direction of the noise, has taken its name Medicine River from this unaccountable rumbling sound, which, like all unaccountable things with the Indians of the Missouri, is called Medicine.

The Ricaras inform us of the Black Mountains making a similar noise, etc., etc., and many other wonderful tales of those Rocky Mountains and those Great Falls.