THE NORTHERN PACIFIC ROUTE. 123 
peak Mount Helena on the west. About 24 miles out the railway 
crosses the Great Northern line to Great Falls and Havre, and near 
this crossing the Red Mountain branch of the Northern Pacific turns 
to the south to a mining district up the valley of Tenmile Creek. 
Beyond milepost 3 Fort Harrison, the largest military post in the 
State, is seen on the left (south). 
Just west of Helena begins the long grade to the summit of Mullan 
Pass. The ascent, 1,618 feet, is accomplished in about 20 miles. 
From Clough Junction, just beyond Birdseye, a branch line leads 
northward to Marysville,' one of the most productive miming camps 
in this vicinity, situated just below the crest of the 
Continental Divide, about 17 miles northwest of 
Helena. 
The rocks in the Front Range in the vicinity of 
Mullan Pass lie on the southwest flank of the great dome whose center 
is north of the Scratch Gravel Hills. The regular southwestward dip 
of the rocks away from the center of this dome is interrupted by a 
small syncline (a downward fold of the rocks) which lies west of the 
summit and also by many intrusions of igneous rock, some of which 
are of great extent, whereas others are small and have had little effect 
upon the general structure. As the rocks on the east side of the 
summit dip toward the range, the westbound traveler passes over 
the several formations in ascending order. 
The rocks are poorly exposed about Birdseye and Clough Junction, 
and the traveler will have difficulty in identifying the Belt series and 
the Cambrian and Devonian formations. Near milepost 11 the 
Louis Mining & Milling Co., which com- 
menced to rehabilitate the milling plant, 
to operate the old workings, then badly 
ved, and to search for new ore bodies. 
Other notable mines in the district 
are the Belmont, Cruse, Penobscot, Bald 
Butte, Empire, and Piegan-Gloster. The 
Birdseye. 
Elevation, 4,231 feet. 
St. Paul 1,139 miles. 
1 The prosperity of the Marysville min- 
ing camp has hinged largely on the for- 
tunes of the Drumlummon mine, the 
oldest, most steadily operated, and most | ca 
productive property of the district. The 
ummon lode was discovered in 
1876 by Thomas Cruse, who had been 
working some placers along Silver Creek 
below the present site of Marysville, and 
the mine was gradually developed by 
him until 1880, when a 5-stamp mill was 
In 1882 the property was sold 
to an English company known as the 
Montana Mining Co. (Ltd.) for $1,500,000. 
During the operations of this company 
1911. the property was sold to the St. 
district has produced about $30,000,000. 
The presence of ore at Marysville is 
due to a small mass of granite that has 
been forced up from below through the 
limestone and shale of the Belt series. 
veins are supposed to ha 
at a later date. 
around the granite have been so thor- 
oughly baked that they are changed into 
hard flinty rocks known as hornstone. 
The ore occurs along the contact of the 
granite and the hornstone. 
