GEOGRAPHICAL MEMOIR. 245 
of forest land. The Hell-Gate river is thus seen to be 130 miles long, flowing for 60 miles 
through the broad and fertile Deer Lodge prairie, which is estimated to contain 800 square miles 
of arable land. Then, taking a direction more transverse to the mountain, opens its valley, 
continues from two to five miles wide, until its junction with the Big Blackfoot, at Hell-Gate, 
after which it widens out to unite with the valley of the Bitter Root. On this part of it there 
are at least 150 square miles of fine arable land in the valley, and much grazing prairie on the 
adjoining hills. Around the Little Blackfoot most of the country is a hilly prairie, suitable for 
grazing, while in the immediate valley is sufficient arable land for the subsistence of a grazing 
population. The Big Blackfoot drains the semicircle from the Hell-Gate to somewhat north of the 
Gate of Sun river; the main stream flowing from the mountains at Cadotte’s and Lewis and Clark’ s 
Pass in latitude 47° 12’ and longitude 119290, In the narrative a very minute description 
has been given of this valley and of its tributary streams; and it will be sufficient in this memoir 
to state that it furnishes undoubtedly at least four passes to the Missouri, two of which have 
been carefully examined in the course of the explorations. "There is, properly speaking, on 
this river, as on the Hell-Gate river, no cañon ; but the term сайоп, which has been used, has 
reference to points where the wide and extensive prairies bordering the river narrow to a com- 
paratively limited space. and is also used to describe passes where there are no special difficulties, 
and where there is in all cases room enough for any kind of construction, looking to the move- 
ment of men and goods. The river itself has a general course a little south of west, winding 
considerably in some parts, but the length of its valley is about seventy-five miles, varying 
from half a mile to twelve miles in width. Neither this nor the Hell-Gate can be considered 
navigable above their junction. Its greatest rise and fall is six feet, as determined by careful 
Observation of its water marks. Оп the 18th July, 1855, its water level was from 8 to 12 inches 
above low-water mark and 5 feet below high-water mark. These streams, together with the 
Bitter Root river, constitute a system of waters flowing from the semicircle, and after their junc- 
tion, opposite Hell-Gate flow in a general course north 45? west to their junction with Clark's 
Fork at the Horse Plain, latitude 47° 21’, longitude 114938'. I have not deemed it necessary 
to speak especially of the western tributaries of the Bitter Root in this general connexion, as 
perhaps they have been sufficiently described in the particular description of the Bitter Root 
valley. Clark’s Fork above its junction with this system of waters at Horse Plain assumes 
another name, and is known as the Flathead river. Indeed, Clark's Fork may be considered to 
be formed by the junction of the two systems of waters, the Bitter Root from the south and the 
Flathead from the north, which, in its turn, drains nearly as large an extent and as fine a 
country as the Bitter Root itself. These two systems of waters, the Flathead "— де Bitter 
Root, are separated by a low mountain spur, which runs from about Stevens’s prairie, on the 
Big Blackfoot, to their junction, opposite Horse Plain. This spur is low, generally well timbered, 
well watered, and a large portion of the land arable. 
Passing from the Hell-Gate to the Flathead river, we cross over this ipar by a low 
divide, going through the Coriacan defile, and coming upon the waters of Jocko river. 
The height of this divide above the Hell-Gate is 560 feet, and above the Flathead riven at 
the mouth of the Jocko, is 650 feet. From this divide a view of карале он looking 
northward, is presented to the beholder. He sees before him an анау rag, 
well-watered, and inviting country. On the east are the divides, clothed with pine, separating 
the Jocko and its tributaries from the streams running into the Big Blackfoot and into Flat- 
head lake ; and along the line of which two rivers Mr. Tinkham moved in September, 1853. 
