258 B. N. A. BOUNDARY COMMISSION. 

596, Fragments of Laurentian, and of eastern limestone, were met 
with on the forty-ninth parallel, as far west as longitude 113° 20’, at 
an elevation somewhat exceeding 4,000 feet. Dr. Hector, examining 
a region further to the north, did not find the ordinary Laurentian 
erratics above 3,000 feet, but described a remarkable line of very*large 
red granite boulders, as occupying alevel of 3,700 feet.** He is uncertain 
whether these may have come from the Laurentian or not ; but taking 
into consideration the absence of granitic rocks on the eastern flanks of 
the mountains in British America, and the fact that such rocks do not 
occur in place over the entire area of the plains, it is highly probable 
that they are of eastern origin. 
597. The estimated height of the highest terraces chases those in 
the mouth of the South Kootanie Pass, is 4,400 feet, and I have little 
doubt but that these are of marine origin. About thirty-six miles north 
of the Line, Lieut. Blakiston measured three terrace levels, and found 
them to be 4,226, 4,176, 4,085 feet, respectively, in altitude above the sea. 
He describes them as “very marked, appearing as a suecession of steps 
from the level of the river to the plain above, often in sight for miles, 
and running horizontally.” Dr. Hector also measured similar terraces 
at the head waters of the Bow, North Saskatchewan, and Athabasca 
Rivers, and states that they ‘ may be considered as ranging on the east 
side of the Rocky Mountains, from 3,500 to 4,500 feet above the sea.” + 
He further says “ until we approach close to the mountains, these 
terrace deposits are confined to the vallies of the larger streams, but 
gradually they spread out, and at last cover ithe whole country along 
the base of the mountains, filling up the hollows and vallies of the outer 
ranges to a depth of several hundred feet.” { ‘ Shingle beds of a similar 
kind are found to cap the Cypress Hills, which have an altitude above 
the sea of 3,800 feet.”” These hills, as has been already stated, are without 
doubt an extension of the plateau of the Lignite Tertiary, and the whole 
of these shingle beds and terraces belong to the deposit which I have 
called the Quartzite drift. Yet further north, on the upper waters of the 
Peace River, Sir Alexander Mackenzie describes the country as step- 
like or terraced as far as the eye could reach, His voyage was made in 
the year 1793, and though not viewing the country with the eye of a 
geologist, he appears to have made remarkably careful and accurate 
observations. 

EE eee — a se aes i Sa 

* Exploration of British North America, p. 221. t Ibid., p. 222, t Ibid., p. 221. 
