94 NATURAL RESOURCES OF THE COUNTRY. 
plough or pick, exposing a smooth and steep surface where undermined by brooks, and sliding at 
a steep angle. ; 
It is not known that any rock excavation will be necessary. Occasionally a spur of coarse 
gray sandstone, in broken detached masses, shoots across the line from the river bluffs, but gen- 
erally not without the opportunity of turning it. ‘I'wo miles of side-cut rock excavation will cover 
this item. 
The grades and curves are probably unequalled by any existing railroad of the same extent. 
On the river-bottoms there will rarely be occasion to exceed the rise of the rivers, by observation 
there being, for the Missouri about one foot to the mile, and for Milk river three feet to the mile. 
The rise from Milk river to the plains is made with a grade of thirty-five feet to the mile. The 
coulées making down to Marias and Teton rivers, aflords opportunity for crossing these streams 
with grades not exceeding forty feet per mile. 
No stream in this section is so large as to require more than a single span of bridge truss. 
Timber trusses will undoubtedly be found cheapest and best in every case. Great Muddy river, 
Poplar and Porcupine rivers, will each require eighty-feet trusses, with two abutments. Milk 
river is crossed in a bend of the stream, at right-angles to the current, is spanned with a truss 
of about two hundred and forty feet, and has an abutment twenty feet high above the river-bottom. 
The masonry of this bridge should be protected, by piling, from the wash of the freshets. Marias 
and Teton rivers will respectively require trusses of about two hundred and twenty and one hun- 
dred and sixty feet length. 
The numerous small waterways required on the bottoms of the Missouri and Milk rivers have 
already been noticed in sufficient detail; as they carry little or no drift-ice and wood, it is not 
necessary to clear their highest water-line more than six feet. 
The supplies of wood accessible are the cotton-woods of Missouri and Milk rivers, the wooded 
mountain termed the “Trois Buttes,’ about sixty miles north of the line, the mountains to the 
south of the Missouri, near Fort Benton, and the Rocky mountains at the end of the section. 
The “black growth” of the streams of the Yellowstone becomes, too, tributary to this section 
at the confluence of this river with the Missouri, near Fort Union, and may be serviceable. 
Of cotton-wood there is an abundance. In certain situations this wood is durable and use- 
ful in building, but, as a railroad sleeper, would soon decay; and being, moreover, soft, would not 
firmly retain the spikes and chains with which the rail is secured. The stockade at Fort Union is 
of cotton-wood, does not rest on the ground, and although erected some twenty or more years 
ago, is firm and sound. A small quantity of red cedar grows on the Missouri, and to some small 
extent will be available in building. The “ Trois Buttes”? above are capable of supplying three 
hundred miles of sleepers, single rail, and probably more if necessary. These Buttes rise about 
3,300 feet above the prairies at their base, and with their wood and stone are a natural storehouse 
of materials. They are wooded for about half the extent, mainly with spruce and a kind of yel- 
low pine, the trees being small, from eight inches to two feet in diameter, and growing straight 
and thickly clustered together. From the base of these mountains a smooth dry prairie extends to 
the route of the railway; and with but little preparation of grading, rails could be laid to bring 
this store of wood to the line of the road. The Rocky mountains afford an abundance of excel- 
lent wood, generally the yellow pine. On the whole this portion of the route may be looked upon 
as capable of supplying sufficient wood, both as fuel and building material, for present and future 
use. 
The lignite of this region, traced from the coulées of Mouse river to the headwaters of Milk 
river, (a distance of five hundred miles) apparently underlying the whole extensive district of 
this country, with a thickness of bed varying from a few inches to six feet, isa source of fuel” 
not to be overlooked. The wooded lands, with proper management and a care for future wants, 
I judge, will of themselves furnish the amount of fuel needed; but our present estimates as to the 
business of a railroad traversing this route, and the wants of settlements growing up from the 
