488 
MISSOURI RIVER FROM GREAT FALLS TO MOUTH OF MILK RIVER. 
are a few small streams, having their sources in springs a few miles inland, which flow into the 
river—and other deep ravines, which appear to be the beds of streams during the wet season; 
but by far the greatest portion of the surface-water is collected in small lagoons, many of which 
are never dry. The soil is harder and dryer than in the prairies previously passed over, and has 
more gravel in its composition. The valley of the James river affords a very little wood, fit only 
for fuel; but between this and the Mouse river, a distance of one hundred and eighty-six miles, 
not a particle, of any kind, is to be found. 
Forty-five miles from the James river my course struck the second terrace, or “ coteau.” 
This is a broad expanse of broken country, more or less elevated above the first terrace—irreg¬ 
ular in its boundary, and irregular in its topography. Sections of it are merely high-rolling, with 
sometimes an extended plateau of comparatively even prairie; while other portions are much 
broken, sometimes rising in abrupt peaks of no great height, and again in long, bare ridges. Small 
lakes are still very numerous, with the peculiarity that the waters of many are more or less salt; 
and, where they may have become partially dried up, white incrustations of salt are found about 
their margins. 
Where I struck the coteau the prairie rose from eighty to a hundred feet in two or three miles, 
and for ten miles was high-rolling and abrupt; but at the end of that distance, with a slight and 
gradual descent, my course struck a gently-rolling plane, that extends, though not in a direct line, 
to that boundary of the coteau that runs nearly parallel to, but at some distance from, the valley 
of the Mouse river. Though obstructions here are not serious, it is quite probable that more 
advantageous lines could be found, to cross this portion of the coteau. 
After striking the valley of the Mouse river, my course to Fort Union coincided so nearly with 
that of the main party of the expedition, that it is unnecessary for me to write of it. 
C. GROVER, 
Lieutenant United States Army. 
Governor I. I. Stevens. 
FINAL REPORT OF LIEUTENANT C. GROVER, OF HIS SURVEY OF THE MISSOURI FROM THE GREAT 
FALLS TO THE MOUTH OF MILK RIVER. 
Sir : I have the honor to submit the following journal and report of a survey of a portion of 
the Missouri river. 
On the morning of the 22d of September, with a crew of three men to manage my craft, I cast 
off from Fort Benton in a small flat-boat and floated down the river. Turning a bend in the 
river, we soon lost sight of Fort Benton and found ourselves shut in from all outward objects, 
between the high banks of the river ; for the Missouri, from its falls for many miles on its way, 
traces its course at the bottom of a deep canon worn by its waters. 
The faces of this canon are generally very abrupt and bare, and approach quite close upon the 
water-course; at the same time determining only the general direction of the river, so that each 
detour of the stream leaves a small rich interval in the bend, covered with luxuriant grass, and 
sometimes skirted with a few small cotton-wood trees. 
About 11 o’clock we passed the site of an old fur-trading post, formerly occupied by Mr. 
Harvey, who has now established one about three-quarters of a mile above Fort Benton. At 12 
o’clock we stopped to lunch where the river flows under a high bank, composed, for nearly a 
hundred feet above the surface of the water, of blue marly earth. Some of the lower portions 
of its surface were covered with a snow-white incrustation of glauber salts, which appeared to 
have been formed by evaporation of water percolating through the face of the bank. 
Continuing on, we soon passed the site of the old trading-post, Fort McKey, marked by the 
remains of an old adobe wall. This fort was burned some years ago by the Fur Company on 
