714 REVIEWS 
installment of the work which is being systematically carried forward 
by the Dominion Geological Survey on these older rocks. The two 
maps, constituting what are known as sheets Nos. 131 and 138 of the 
Canadian Series, lie in the Upper Ottawa district along the border of 
the two Provinces of Quebec and Ontario, and comprise portions of 
both. Lake Nipissing and Lakes Temagami, ‘Temiscaming, and Kee- 
pawa, as well as many smaller bodies of water, are included in the 
area, and afford along their shores especially good opportunities for 
the prosecution of geological work. 
After presenting a general account of the early explorations in this 
region, some of which date back almost to the time of the earliest 
settlement of the country by the French, and of previous surveys, the 
physical features of the country are described. ‘The area is a great 
uneven, or gently undulating, rocky plateau, sloping somewhat to the 
east and southeast, having a general elevation of goo to 1200 feet 
above sea level, the level being so nearly uniform that hills 50 to 100 
feet higher are conspicuous topographical features. This peneplain is 
traversed in a north and south direction along one line by a very deep 
and narrow rocky gorge, in which lie Lake Temiscaming and the Ottawa 
River. The hills, or cliffs, rise to a height of 400 to 600 feet from the 
water on either side, while the water of the lake is 4oo feet deep; the 
bottom of the gorge being filled with a fine silt. The depression is 
thus at least 1000 feet deep and represents a great canyon similar to 
those which are found on the margin of the northern Protaxis at so 
many other points. Several smaller rivers also occupy similar depres- 
sions. “The detailed examination of the region, however, amply 
demonstrates that the sculpturing to which the surface owes its present 
configuration was practically completed long before the advent of the 
glacial epoch, and that the main valleys, especially those of the Ottawa 
and Mattawa rivers, were in existence long prior to the deposition of 
the Palaeozoic sediments.” With the exception of some comparatively 
small areas occupied by Palaeozoic outliers, ranging in age from Black 
River to Niagara, the district is underlain by rocks of Laurentian and 
Huronian age. The Laurentian, with the exception of a few small 
occurrences, is represented exclusively by the fundamental gneiss, a 
mass of granitic and dioritic rocks, usually possessing a foliated 
structure in which are many streaks, bands, or inclusions of basic 
character, allied to diorites or diabases in composition, and represent- 
ing either basic segregations from the granitic magma or portions of 
