634 LETTER OF LIEUTENANT MULLAN. 
ridge, I fell upon three of the head branches of the Wisdom river, the principal tributary to the 
Jefferson fork of the Missouri; hence to thy main stream, crossing the northwestern branch, being 
the one followed by Messrs. Lewis and Clark in their expedition to the Pacific in 1804 and ’5, 
and following up the southeastern branch to near its head by a very beautiful, easy road to the 
dividing ridge of the Snake river waters, crossing by a very good road for pack animals, but not 
for wagons. Here we fell upon the Medicine Lodge creek, which I followed down for twenty 
miles ; leaving it to my right, at the distance of twelve miles it forms a lake called “ Medicine 
Lodge lake ;” crossing the sage plain of Snake River valley for a distance of fifteen miles, we fell 
upon a small mountain stream called the Camash Prairie creek, which also forms a lake in the 
great sage plain of Snake River valley ; thence across the sage plain to Snake river, or Lewis’s 
fork of the Columbia, which I followed down for two days, crossing it by a ford with two anda 
half feet of water, about twenty-one miles east of Fort Hall, where I arrived on the 15th of De- 
cember, 1853. From the St. Mary’s village to the waters of the Missouri, we found the grass 
rich and luxuriant, and wood in adundance. Scarcity of timber and barrenness of soil character- 
ized the remainder of the route to Fort Hall, except a few localities along the Snake river, where 
we found an abundance of wood, and very good gra-s. Remaining at Cantonment Loring five 
days to recruit my animals, I left on the morning of the 19th, intending to return by a new and 
different route; keeping along the eastern base of the Bitter Root mountains, or main chain: f the 
Rocky mountains. You will see that from the route followed to Fort Hall, we crossed the divid- 
ing ridge of the Missouri and Columbia waters twice. This was necessary from the peculiar 
configuration of the mountain ranges, which are so formed as not to allow of a practicable route 
by keeping west of the main chain of the Rocky mountains the whole distance. The whole chain 
of mountains from Bitter Root valley to Fort Hall is formed of smaller ridges or chains, arranged 
in beds, as it were, with beautiful prairie valleys intervening, through which flow mountain 
streams, covered with timber, and covered with an abundance of rich grass, thus giving excellent 
recruiting stations, or rendezvous for the Indians, with their large bands of horses. From the 
Snake River mountains to Lewis’s fork of the Columbia the country, as far as I travelled, is char- 
acterized by the exceedingly great abundance of the artemisia or wild sage found growing; 
scarcity of grass; extreme barrenness of the soil, which is covered in most places with large beds of 
black, honey-combed, volcanic rock, which latter is the great geological feature that characterizes 
the country for hundreds of miles along the Snake River valley. From the St. Mary’s village to 
the waters of the Jefferson fork of the Missouri the geological formation is principally granite and 
gneiss. On the waters of Jefferson river and its tributaries the geological features are completely 
changed, the formation becoming limestone and conglomerate principally. 
In returning from Fort Hall I continued on the same route till arriving at the main stream of 
the Jefferson river. Here our course lay more to the east. Crossing the Jefferson river we fell 
upon the main stream of Wisdom river, a few miles above its mouth, passing between the 
* Rattlesnake Bluffs’? and “ Beaver’s Head,” two prominent and well-known landmarks of the 
valley of Jefferson river. These names were given them by Messrs. Lewis and Clark. ‘This 
stream I followed to one of its head branches—to the dividing ridge of the Hell Gate river 
waters, which we found to be a low divide, of easy ascent and descent. My course lay down 
the valley of the main branch of the Hell Gate river to its junction with the “ Little Blackfoot _ 
Fork,” which latter stream was followed down from its head, both by Mr. Tinkham and myself, 
in our respective reconnaissance from Fort Benton ; and I would here remark that this stream of 
the “ Little Blackfoot Fork”? has been miscalled both by myself and Mr. 'Tinkham: we took it to 
be, and have given to it the name of, the Hell Gate river, and I avail myself of this opportunity 
to correct the error. The stream followed down by the main train from Fort Benton was the 
“Big Blackfoot Fork,” and not the “ Blackfoot Fork.” My return route from Fort Halllay over 
a much better though longer road than the one followed in going south, and is by far the better 
wagon road; in a word, there is no difficulty whatever in the passage of wagon trains by this 
