THE NORTHERN PACIFIC ROUTE. 131 
West of Bearmouth the lava forms the walls of the canyon for a 
distance of 2 miles to the mouth of Harvey Creek, a small stream 
entering the river from the south. Opposite and a little below the 
mouth of this creek there is a syncline extending to the northwest. 
The rocks in the middle of this basin are the red shale and sandstone 
of the Kootenai, rimmed about by lower and older formations, the 
lowermost of which are the limestones and quartzites of the Carbon- 
iferous. 
About Blakeley siding and for several miles west of it the rocks 
on both sides of the canyon are red shale or argillite and red sandstone 
belonging to the Spokane shale (Algonkian). ‘This is the first appear- 
ance in the westward journey down Clark Fork of this red argillite, 
which makes most of the walls of Hell Gate Canyon from Blakeley 
siding to Missoula. 
Blakeley siding is well within Hell Gate Canyon, the principal 
highway by which the white man in the early days and the Indian 
before him crossed this mountainous region. The first permanent 
wagon road in this part of the country was built in this canyon in 
1859-1862, and is known from its builder as the Mullan road. Its 
construction is intimately associated with the early development of 
the country, and a more extended account is given below.’ 
Pa ‘al Je Ay es Ye 
1 Hell Gate Canyon is one of the great 
natural thoroughfares of the continent. 
Through this canyon the Flatheads and 
other tribes of the West journeyed to the 
plains annually to hunt the buffalo, and 
forays against their more peaceful neigh- 
bors on the west. 
In 1853, when the Government engi- 
neers were exploring the various passes 0. 
the Rocky Mountains to find the most 
should connect Fort Benton, then the 
head of navigation on the Missouri and 
the most prominent post on the east side 
of the mountains, with Fort Walla Walla, 
which was of equal prominence on the 
Pacific slope. Lieut. John Mullan was 
the most ardent advocate of a military 
road, but he was ably seconded by Gov. 
Stevens, the leader of the expedition. 
The location of such a road east of the 
so in 1854 Mullan explored three possible 
in defer to deteemine the best location. 
These were A) Clark Pork, _— shine 
Oreille 
was not then in existence); (2) the St. 
Regis and Cceur d’Alene valleys; and (3) 
the = trail. 
and Clark had already aaa 
over “the Lolo trail and had give 
Mullan, who devoted most of his energies 
to the other two routes. The route first 
mentioned, along which the Northern 
Pacific Railway was subsequently built, 
was partly explored by Mullan in 1854, 
but unfortunately the attempt was made 
in May, when the snow in the mountains 
was melting rapidly, — he had work 
ble on account of high water, so he rela 
Mullan then ‘explored the St. Regis and 
Coeur d’Alene valleys and decided that 
