234 GEOGRAPHICAL MEMOIR. 
dried up in the summer season, affording, however, water for camping purposes. There are 
some lakes in this genial region, and many in the cóteau itself. The voyageurs of the country 
state that there are numerous lakes all along the cóteau as far as James river, and it is unques- 
tionable that they will supply any deficiency of water along the salt water region south of the 
Miniwakan lake. There is no doubt, however, that this portion of the route can be readily 
supplied by means of artesian wells. It may be estimated that fifty miles of the country on 
and in the neighborhood of this cóteau is not continuously cultivable. There are through it, 
as in the region referred to south of the Devil's lake, many spots of good land, in the valleys 
of the streams, on the shores of the lakes, and in the hollows and depressions of the country. 
The mouth of the Yellowstone is a great landmark throughout this whole country, and, in 
geographical position and importance, is worthy of special mention. Here the two great 
branches of the main trunk of the Missouri come together; to this point, and sometimes above 
it, steamers of from four to six hundred tons have come from St. Louis every year for the last 
twenty-five years; and it may become hereafter a depot for supplying the Salt Lake, by the 
line of the Yellowstone, which is navigable for boats, and possibly for steamers, to above the - 
mouth of the Big Horn, a distance of about two hundred miles. The character of the Missouri 
above Fort Union will be referred to more specifically hereafter. It may be said here, however, 
that its waters are navigable for steamers to within less than one hundred miles of the divide 
of the Rocky mountains. қ 
The general region of country described thus far is between the 92d and the 104th degrees 
of longitude, an air-line distance east and west of 575 miles. The dividing ridge of the Rocky 
mountains and the scope of country included within the purview of the northern route is in the 
112th degree of longitude, on the parallel of 46°, taking a northwesterly direction to the 115th 
degree of longitude, in parallel 49°. 
MOUTH OF THE YELLOWSTONE TO ROCKY MOUNTAINS.—DESCRIPTION OF ТНЕ UPPER MISSOURI RIVER 
AND ITS TRIBUTARIES. 
The Missouri may be described as. follows: It has its source in three main tributaries, the 
Gallatin, Madison, and Jefferson forks, between the 44th and 45th parallels. These streams, 
by their junction, form the Missouri, in about latitude 45° 24’ and longitude 110° 40’. Thence 
_the general course of the Missouri is northward, ranging within from twenty-five to sixty miles 
of the divide of the Rocky mountains, when it breaks through a somewhat difficult projecting 
spur of the same, at a point denominated by Lewis and Clark the Gate of the Mountains; 
continuing then to the northward, and soon varying to the eastward, we come to its Great 
Falls, which may be described as follows: They consist of five principal cascades, commencing 
three miles below the mouth of Sun river, and extending for 114 miles, with intervals of rapids 
between them. The entire fall amounts to 160 feet, and varies from 5 feet at the second pitch 
to 16 feet in the last, the first being 25, the third and fourth 42 and 12 feet, respectively, 80 
that the increase is nearly in geometrical progression from the least to the greatest. | 
The banks are high and abrupt on both sides, intersected by ravines, but opposite the fall on 
the north side a strip of rolling prairie runs near the river and breaks off in terraces to a small 
bottom below the cascade, from which to Fort Benton a passage along the river bank can be 
made practicable by cutting through some projecting bluffs. Thence its general course is nearly 
due east, until we reach Fort Union. From the Great Falls to Fort Benton, a distance of 30 miles, 
it gradually widens; and here are more and larger points of bottom land on its banks, to Highwood 
