That the region, however, has been submerged in later times is attested surface, rather than where igneous basalt flows on the slopes may 
by the presence of smaller patches of paleozoic sediments resting on the have become hard tempered when deposited or thrust out in surrounding 
flattened surface of the older rocks. waters. It may be that there they found their “line of least resistance.” 
As the valuable metallic deposits of this Northern area belong to It may also be that the sediments overlaid as an elastic spongy mass in 
the class of ores deposited from solutions that derived their dissolved places forcing the mineral laden waters into fissures, fractures and 
substances from cooling igneous material such as intruded batholiths of breaks. 
granite, etc., it is safe to assume that the granites and the porphyries After a long period when climatic conditions changed from tropical 
were the gold bearers, although they do not all penetrate to the surface. to intense cold a Continental ice field was formed stretching from a point 
Leaving the cooling batholithic intrusive, the magmatic solutions south of the Great Lakes to the North Pole and beyond. Later, warmer 
which carried the metals were forced upward under great pressure, and climatic conditions prevailing, portions of the ice field moved southward 
penetrating through fissures and other planes of weakness in the vol- in what was known as the glacial age. This planed off a part of the 
canics and sediments were deposited in these older rocks. Such deposits sediments and also the basalts where they were not covered or were 
were formed probably several thousands of feet below the land surface thinly covered by sediments, conglomerates, etc., and the deposition and 
existing at the time, but erosion has cut down so deeply that this deeper mineralization were in places left exposed on the present surface. The 
zone to-day lies exposed on the present land surface ready to yield up amount of erosion by the pleistocene ice sheet was very small, and the 
its deposits to careful and intelligent prospecting. Where previous whole continental ice field in bulk did not move southward. The glacial 
intrusions caused shearing and twisting movements these shear zones moraine moved little in places, as is particularly evident at the Clarke 
were exceptionally favourable for the deposition and retention of valuable property on the Harricanaw River in Northern Quebec, where square 
gold deposits. boulders of quartz with visible gold undoubtedly came from the big 
It will be appreciated that, in the cooling, the temperature would surface gold vein ‘two lumdred feetitoitheinorthward. 
fall rapidly as the distance from the parent super-heated body increased, We can draw a further deduction as to the prospecting value of 
and that at a certain temperature, i.e., at a certain distance from the these main Continental heights of land from the fact that precious metals 
intrusive batholithic body, precipitation would occur and a zone would dividend payers have so far not been found in Northern Ontario or 
be created in which this mineralization could proceed. It would follow Northern Quebec more than fifty to sixty miles distant from these main 
that this zone of mineralization would in general lie more or less parallel Continental heights of land. 
to the surface of the present igneous body, and would be a greater distance Whatever opinions may be held as to the existence of a definite 
from a large batholithic intrusion of many miles in length than from a relation between the occurrence of precious metals mineralization and 
smaller one of a few miles or less in length. these Continental heights of land, such as the Rocky Mountains from 
The adjacent area round the small granitic intrusion may then be Mexico through Colorado, Montana and British Columbia to the Klon- 
more favourable for the finding of surface enrichments. In the case of dike, and also this easterly height of land running from Labrador across 
large intrusions such as the granitic masses some distance south of the north country into the Rockies separating the waters of the Arctic 
Rouyn the rocks must have been so intensely heated that any mineral from the Gulf of Mexico, it appears, as has been previously pointed out, 
bearing solution given off by them would probably be driven too great a that the most important discoveries have been made at points close to 
distance to be correlated with the intrusion. its present existing position. 
Probably conditions were made much more favourable for the As favourable prospecting conditions up North are found along the 
intrusion and deposition of these super-heated mineralized waters in exposures on these heights of land, prospectors when they weigh the matter 
economic volume through and along the horizon of the main volcanic fully, are likely to explore it thoroughly. These sections are now well 
range where vents and fissures from great depth led up closer to the served by the Canadian National Railways. 
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