216 National Geographic Magazine. 
great Missouri and one of its principal branches, the Yellowstone 
River, rise in these mountains and after flowing northward 
nearly to the British line turn and flow eastward and join the 
Mississippi on its way to the Atlantic. 
The highest mountains in Montana are in Park, Gallatin, 
Madison and Beaver Head Counties, in which latter the further- 
most branches of the Missouri, the Beaver Head and Big Hole 
Rivers, which form the Jefferson river, have their sources at the 
summit of the Rocky mountains, and it was here that those 
intrepid explorers, Lewis and Clarke, first crossed the Continental 
Divide in 1805 to the headwaters of one of the branches of the 
Snake river. 
In these counties a few of the highest peaks reach an elevation 
of 11,000 feet, and from here the main range of the Rockies bears 
off to the north in a long, continuous and rugged ridge of sand- 
stone and porphyry, with extensive beds of limestone north of 
the headwaters of the Dearborn River, and gradually falling off 
in elevation, until near the British line the highest peaks are less 
than 7,000 feet above the sea. 
From this same axial point in the southwest corner a main spur 
or branch of the Rockies, called the Bitter Root Mountains, bears 
northwesterly and falling away in height, gives out with an eleva- 
tion of 2,200 feet in northern Missoula County where the Clarke’s 
Fork river leaves the State, cutting across the foot of this range. 
East of Madison ‘and Jefferson Counties, and along the 
southern border of the State, are numerous short mountain 
ranges, often 10,000 feet and sometimes 11,000 feet in elevation, 
which have generally a north and south trend and fall off near — 
the middle of the State to a continuous, broad, and nearly level 
high prairie, or as it is locally called “bench land,” which con- 
tinues to fall slowly in the same direction. 
Do not imagine that these great ranges of mountains are wild 
and uninhabited for such is not the case ; they are merely great 
mountain masses, and between, among and on top of them are 
other minor ranges of mountains, usually having symmetrical 
and regularly slopimg sides, which are separated by broad, level 
and very fertile valleys, everywhere inhabited and cultivated by 
the aid of irrigation, while herds of cattle, horses and sheep graze 
on the hillsides. 
Even among the roughest mountains a man may travel alone 
on horseback sure of finding shelter and food somewhere in the 
