ROUTE NEAR THE FORTY-SEVENTH AND FORTY-NINTH PARALLELS. 
49 
from tlie Pend d’Oreille lake to Horse Plain. Rails will undoubtedly he required at several of 
the places, and transfer he made from steamer to steamer.” 
The total length of the route from St. Paul to Seattle, Puget sound, by the Columbia River 
Pass, is 2,025 miles, or 2,050 if the Bitter Root river is used instead of the Jocko; by the 
Yakima Pass, 1,8*70 and 1,845 miles respectively. The distances just given are taken along 
the line of location for the proposed railroad. They are nearly the same as those travelled, 
except on the prairies east of the Rocky mountains, and on the Spokane Plain, where the 
located line is shorter than that travelled over, there being no serious obstacles to the more 
direct course. The distances given differ from those used by Governor Stevens, owing to a 
revision which the maps have undergone since his report was written. 
SOIL. 
In the absence of the geological report of Dr. Evans, whose field duties in Washington 
and Oregon Territories have detained him there until recently, the information upon the 
character of the soil upon the route is not as full, detailed, and satisfactory as could be 
desired. Previous geological examinations, over portions as far west as about longitude 101° 
or 102°, show that the uncultivable region begins in about the same longitude on this route as 
in the latitude of the Arkansas. 
From the geological information respecting the region between the meridian of 101° and 
the Spokane Plain imparted recently by Dr. Evans, from the report of Mr. Gibbs upon the 
section west of the Spokane, and after a close examination of the reports, the following 
general conclusions have been arrived at respecting the soil of the region traversed by the 
northern route. 
From the Mississippi to the western border of the Plateau of the Bois des Sioux, in about 
the meridian of 98° west of Greenwich, the soil is fertile; the upper layer being composed of 
vegetable mould. Here it begins to be mixed with sand and gravel, the proportion of which 
ingredients increases as you proceed westward. From Fort Union to the foot of the mountains, 
(15 or 20 miles east of the crest,) the upper covering of sand, clay, and gravel is from one to 
three feet thick, and lies upon a coarse sandstone. The grass, luxuriant on the vegetable mould, 
gradually becomes thinner, until on the sterile soil it is very sparse. Immediately under 
the mountains it improves again—perhaps from the intermingling of limestone debris, and 
the comparatively greater fall of rain. 
On the Coteau du Missouri the ground is rougher, and the grass thinner, than on the 
prairie; and west and south of the Missouri it is in many places even yet more rough and 
sterile, the Mauvai'ses Terres beginning not far from the mouth of L’Eau-qui-court river. 
In fact, the tertiary and cretaceous formations extend from about longitude 97° west of 
Greenwich to the eastern base of the Rocky mountains; the soil being stiff clay and sandstone, 
alternating with each other. The former are well constituted for fertility; but, under the pres¬ 
ent meteorological conditions, (the small yearly amount of rain, and the total absence of it 
at certain seasons,) they are unsuitable for agricultural purposes. They produce luxuriant 
grasses in the spring, but in the dry season (the summer) the sun withers the grass; parches, 
bakes, and cracks the clay surface, and not only gives it a sterile aspect, but renders it unculti¬ 
vable. The sandstone soils are in themselves sterile. It is thought by some that if the annual 
burning of the prairies were to cease, forests would grow upon the clay soils, a greater amount 
of rain in the summer be precipitated by them, and that these clay soils would thus become 
cultivable. 
The river-bottoms in part (where the soils of the different strata become mixed,) and the val¬ 
leys among the mountains, form exceptions to this general condition of sterility. As, for 
instance, it is Lieut. Donelson’s opinion that upon the Missouri the soil is such that the set¬ 
tlements might be continuous upon its banks up to the mouth of L’Eau-qui-court river, longi- 
7a 
