[ELLS & BARLOW] PROPOSED OTTAWA CANAL 179 
Petawawa rivers to the Ottawa, a route approximately parallel to that by 
the Mattawa and Ottawa, and, in the ensuing year,’ he made further 
explorations in this area by a traverse towards Lake Nipissing along the 
Meganatawan River. In 1855 he completed the examination of this sec- 
tion by the exploration of the Nipissing and French River route.’ In his 
descriptions of the several sections then examined Murray enumerates the 
usual variety of red and gray gneiss, micaceous and hornblendie schists, 
quartzite and crystalline limestone, as well as certain areas of reddish 
syenitic rock, in which the stratification was entirely absent or very 
indistinet, which were regarded as probably intrusive; while the country 
rock generally was held to be metamorphic. The whole series was found 
to be everywhere corrugated, often with steep bends and folds, and inter- 
sected by quartzo-felspathic dykes and quartz veins. 
The gradual evolution of the problem of the composition, origin and 
structure of these oldest Laurentian rocks which were so extensively 
studied by Logan, Murray and Hunt prior to 1863, required much care- 
ful study, both in the field and laboratory. The difficulty of arriving at 
satisfactory conclusions in the field at that early date can be sc arcely 
appreciated at the present day ; since forty years ago much of the area 
covered by the Laurentian rocks was accessible only with great trouble 
and expense, while the men skilled in the interpretation of such a com- 
plicated geological structure as was thus presented were few. The pro- 
blem undertaken by these pioneers in Canadian geology was not only new 
but one of exceeding difficulty, yet the results then arrived at, with the 
limited means at their disposal, have been accepted as conclusive by most 
workers in this field for many years. The more recent field work 
Lawson * on these rocks as developed to the west of Lake Superior about 
the Lake of Woods and elsewhere, and by Barlow‘ in the country north 
of Lake Huron, gradually led to the conviction, on their part, that much 
of what had been regarded as the oldest member of the Laurentian, viz., 
the syenitic gneiss, destitute of limestone, was of more recent age than the 
stratified gneiss and limestone series with which they were associated ; and 
that, in fact, these had been intruded into the gneiss at a date subsequent 
to their deposition, 
An examination by Dr. F. D. Adams in 1885-86, of the great anortho- 
site areas of Morin and the townships adjacent, which had been regarded 
as the upper part of the Grenviile sedimentary series, led him also to 
the conclusion that these could no longer be regarded as altered sediments 
but that the anorthosite was clearly intrusive through the Laurentian 


1 Con Survey Report, A. Murray, 1853-56. 
2 Tbid., 1853-56. 
3 Geological Survey Report, vol. iii., new series (F), A. C. Lawson, 1887-88, ‘‘ On 
the Rainy Lake region.” 
“4 American Geologist, vol. vi., pp. 19-32 (July, 1890) ; Bulletin G. S. A., vol. iv., 
pp. 313-332. 
