EOCKY MOUNTAIN SHEEP. 
167 
man to climb up one of these extraordinary conical hills, as they are slip- 
pery, greasy and treacherous. Often '.vheii a big horn is seen on the top of 
a hill, the hunter has to ramble round three or four miles before he can 
reach a position within gun-shot of the game, and if perceived by the 
animal, it is useless for him to pursue him any further that day. 
The tops of some of the hills in the “mauvaise terres” are composed 
of a conglomerated mass of stones, sand, clay and various coloured 
earth.s, frequently of the appearance and colour of bricks. We also 
observed in these masses a quantity of pumice stone, and these hills, 
we are inclined to think are the result of volcanic action. Their bases 
often cover an area of twenty acres ; there are regular horizontal 
strata running across the whole chain of these hills, composed of different 
coloured clajq coal and earth, more or less impregnated with salt and other 
minerals, and occasionally intermixed with lava, sulphur, oxide and sulphate 
of iron; and in the sandy parts at the top of the highest hills, we found 
shells, but so soft and crumbling as to fall to pieces when we attempted 
to pick them out. We found in the “ mauvaise terres, ” also, globular 
shaped masses of heavy stone and pieces of petrified wood, from frag- 
ments two or three inches wide, to stumps of three or four feet thick, 
apparently cotton wood and cedar. On the sides of Some of the hills 
at various heights, are shelf-like ledges or rock projecting from the 
surface in a level direction, from two to six and even ten feet, gene- 
rally square or flat. These ledges are much resorted to by the big horns dur- 
ing the heat of the day. Between these hills there is sometimes a growth 
of stunted cedar trees, underneath which there is a fine sweet grass, and 
on the summits in some cases a short dry wiry grass is found, and quanti- 
ties of that pest of the Upper Missouri country, the flat-broad-leaved Cac- 
tus, the spines of which often lame the hunter. Occasionally the hills 
in the “mauvaise terres” are separated by numerous ravfines, often 
not more than ten or fifteen feet wide, but sometimes from ten to fifty feet 
deep, and now and then the hunter comes to the brink of one so deep and 
wide as to make his head giddy as he looks down into the abyss below. 
The edges of the canons (as these sort of channels are called in Mexico) 
are overgrown with bushes, wild cherries, &c., and here and there the Bison 
will manage to cut paths to cross them, descending in an oblique and zig- 
zag direction ; these paths however are rarely found except where the ra- 
vine is of great length, and in general the only mode of crossing the lavine 
is to go along the margin of it until you come to the head, which is gen- 
erally at the base of some hill, and thus get round. 
These ravines exist between nearly every two neighbouring hills, al- 
though there are occasionally places where three or more hills form only one. 
