130 GUIDEBOOK OF THE WESTERN UNITED STATES. 
turning of the side of the syncline was probably produced by a strong 
thrust from the southwest which not only caused the rocks to fold in 
the form of a trough, but continued and pushed the rocks composing 
the side of the fold far toward the middle of the basin. 
Below the cliff of limestone the stream is very tortuous, winding 
from side to side of the synclinal basin in which it is flowing. The 
railway originally followed all the crooks and bends of the stream, 
but now it pursues nearly a straight course, cutting through the 
points and bridging the stream, or diverting its course where diversion 
could be accomplished readily. The deep cuts across the projecting 
points in the bends of the stream afford an excellent opportunity 
to see the dark-red shale of the Kootenai formation, which is exposed 
in the middle of the trough. 
At milepost 79 the river, accompanied by the railway, turns to the 
southwest and cuts across the rim of the syncline, which is made up 
of hard, massive limestones and quartzites (Carboniferous). As 
these rocks always make rugged and picturesque canyon walls, it 
is well for the traveler who wishes to obtain a good view to be ready, 
as it takes only a minute or two to pass through the interesting part 
of the gorge. Just below milepost 79 the railway crosses the Quad- 
rant quartzite, which makes little showing on the hill slopes. This 
is soon passed, and then the massive layers of the Madison come 
into view. As the course of the road changes more toward the north- 
west, the limestone beds can be seen rising in great cliffs on the left, 
but beyond another bend to the west they appear in all their rug- 
gedness in the wall on the right. The limestone, stained red or 
rather splotched with red, rises on both sides to a height of 500 or 
600 feet; and the rock is carved into the most fantastic shapes, such 
as pillars, needles, towers, and minarets—in fact almost every form 
the imagination can*conceive. The combination of rugged forms 
and striking colors gives to this canyon a character of its own that 
would be hard to duplicate in any other region. The limestone on 
the southwest rests against a mass of lava (andesite), which covers 
much of the country southwest of the river and is exposed in its 
bluffs in the vicinity of the next station, Bearmouth. 
Opposite Bearmouth a small stream, Bear Gulch, enters the river 
from the right. Here gold-bearing gravel was discovered in October, 
1865, by a party under the leadership of Jack Rey- 
Bearmouth. nolds. In the two years following its discovery 
ae produced $1,000,000, and later the yield was 
St. Paul 1,210 miles, Inereased to many times that amount. The placers 
are no longer worked, but it is said that gold-bearing 
quartz veins have been found which may some day bring new activity 
to this region. 
