THE NORTHERN PACIFIC ROUTE. 149 
uppermost beach line here probably corresponds with the highest 
one observed near Missoula and Dixon and, as these beach lines were 
formed by the same body of water and therefore must have been 
horizontal, it is almost certain that the crust of the earth has been 
tilted since the disappearance of the lake, the surface about Missoula 
having been raised 1,000 feet above that at Trout Creek, as explained 
on page 134. 
Just beyond milepost 59 the roadway is cut in the base of a high 
cliff which is composed of Newland limestone lying nearly horizontal. 
The argillites and quartzites showing across the river and in the 
pyramidal island in the stream are vertical, hence there must be a 
fault between them which coincides in a general way with the course 
of the river. 4 
Near milepost 67 a charming view is to be had of the cliffs on the 
south, which stand like a huge castle with battlemented walls. 
The Newland limestone is exposed almost continuously along the 
river from milepost 59 to Noxon and for some miles beyond. It is 
generally horizontal or dips slightly to the northwest. 
Noxon. Nearly opposite milepost 74 Bull River joins Clark 
eee eee ee seem the north. This tributary valley is con- 
oer ected by a broad, deep trench directly through the 
Cabinet Mountains with the valley of Lake Creek, affording in glacial 
time a direct outlet for the great mass of ice that kept crowding down 
from the northern country. In this great trench the ice at its maxi- 
mum was at least 2,000 feet deep. As soon as it emerged into the 
more open valley of Clark Fork it was reinforced by a large ice tongue 
that came down by Sandpoint and deployed up the Clark Fork valley. 
These two masses blended and filled the valley from Pend Oreille 
Lake to Noxon, forming an effective barrier across the pathway of* 
the stream. Behind this barrier the body of water known as glacial 
Lake Missoula accumulated. In its passage up the valley the glacier 
left abundant evidence of its presence and work by the scouring which 
the valley received, the scratches on the rocks, and the bowlders of 
granite and other crystalline rocks which it carried into this area, 
The bowlders were not only dropped upon the valley floor, but many 
of them were left stranded on the valley wall up to a height of at 
least 2,000 feet above the stream. 
Beyond Bull River there is little of interest for some distance. 
The valley walls are composed of Newland limestone, 
Heron, Mont. which dips gently downstream. Just beyond mile- 
ee post 87, 8 Tew miles west of Heron, the train crosses 
Paul 1,398 miles. 47, State line into Idaho, the boundary being indi- 
cated by a signboard. 
