THE NORTHERN PACIFIC ROUTE. 119 
the river and it is visible up the hill slope beyond milepost 190, where 
the train crosses a spring that wells up in large volume from the 
limestone. The spring forms a beautiful pool, and the stream that 
flows from it is carried in ditches for a long distance and used to irri- 
gate the bottom land farther down the river. 
About 1,000 feet beyond milepost 191 the fault is crossed for the 
last time, and here the conditions are much like those that prevail at 
the other crossings. The rocks south of the fault carry a coal bed 
similar to the one opened near Lombard, and the formation is in 
contact with a large mass of igneous rock which on the other side 
rests against the rocks of the Belt series. The Belt rocks are con- 
siderably altered, apparently by the heat of the intruded mass, and 
some mineralization of the rocks has been the result, but although 
many prospect pits can be seen on the hillsides, little of value has 
been found. 
The hard rocks that form the high hills soon give way to the soft 
clay of the lake beds, and at Toston the valley opens out on both sides 
nearly as far as the eye can reach. The river has no 
Toston. well-marked channel, and its surface is only a few 
Elevation 3,925 feet. feet below the general level of the plain. This is the 
= cong ae result of the washing in of fine silty material, in which 
"the valley has been cut. The valley was originally 
formed by some downward movement in the crust of the earth (see 
p. 112) and then it was occupied by a lake, probably an extension of 
the body of water that occupied Gallatin Valley in Miocene time. 
After the lake basin was filled or drained the land was raised, an 
Missouri River has carved its present valley almost entirely in the 
soft materials laid down in the old lake. Owing to the softness of 
this material it is washed into the river at every shower and so the 
stream is supplied with more sediment than it can carry. This 
material therefore settles to the bottom, and the channel of the stream 
is kept at nearly the same level as the bottom land on either side. 
Opposite milepost 201 the hills on the left closely approach the 
river bank and for a height of 400 feet they appear to be composed 
entirely of clay deposited in the old lake. oo 
The flourishing town of Townsend (see sheet 17, p. 126) is in the 
heart of a prosperous agricultural region which stretches up and down 
the river valley for a long distance. A little beyond 
Townsend. the town the railway crosses Missouri River and 
levation 3,833 feet. begins to climb to the top of the terrace that faces 
Population 759. the river. From this point the traveler may obtain, 
: : 
t. Paul 1,098 miles. on the right, a broad view of the fertile farms stretch- 
ing across the level bottom of the Missouri and broken only by lines 
