tocks carry soft coals or lignite, but have not been shown to contain oil, gas, or metallic mineral deposits of value. It will be seen that in the great valley of the Mackenzie there are conditions indicating possible oil occurrence covering an area of varying width and over 1,000 miles long—the greatest unexplored, or practically unexplored, potential oil area on the continent. METALLIFEROUS DEPOSITS Within the North Pacific Region there are three broad zones favourable for mineralization: (1) The contact zones of the Coast Range, with certain outlying but related mineralized areas within the Interior Plateaux. | (2) The contact zones of the Cassiar-Omineca batholith { and its extension, with associated granitic intrusions in Yukon. (3) The western fringe of the Precambrian Shield adjacent to the Great Central Plain. The contact zones of the Coast Range stretch roughly from the Alaska border in Yukon to the valley of Nass River in British Columbia. In Yukon, the mineral deposits of the contact zone are distributed in two belts: one em- braces the northeast flank of the St. Elias Mountains and the valley between them and the Coast Mountains; the other follows similarly the northeast flank of the Coast Mountains. To the south, in British Columbia, the mineralized zone lies on the eastern side of the Coast Range, stretching as a narrow belt through the Atlin section, and the lower Stikine and Taku Valleys to the Portland Canal, Anyox, and Alice Arm areas. East of the contact zone, metallic mineralization occurs at Telegraph Creek, Meziadin Lake, and in the Rocher Déboulé Range at Hazelton. _ The contact zones of the CassiarOmineca batholith in British Columbia offer favourable prospecting ground for metallic minerals, and some degree of development has proceeded on both its eastern and western flanks. The eastern belt lies west and roughly parallel to Parsnip and Finlay Rivers (Rocky Mountain Trench) and extends through to the border territory east of Dease Lake. A similar parallel zone west of the batholith is geologically favourable but has not been prospected extensively, and, outside the Dease Lake area, has not been examined geo- logically. It has been suggested that the northward extension of this zone may be the source of the Yukon placer deposits. Its continuation in Yukon, although not sharply defined, includes the Klondike placer goldfields and the Mayo silverlead camp, the two main productive areas of Yukon. Bounding the North Pacific Region on the east and northeast is the western border of the Precambrian Shield, along which important mining operations have developed over the past decade. [ 28 ] Metallic mineral occurrences are -by no means exhausted. widespread over a belt extending northwestward from the North Arm of Great Slave Lake to Great Bear Lake. This belt includes the Yellowknife district. The Pine Point lead-zine deposits on Great Slave Lake lie to the south. Despite the extent of areas favourable for mineralization and the diversification of metallic mineral occurrences, most of the potential mineralbearing part of the North Pacific Region remains comparatively inactive. Preliminary geological reconnaissance and mapping have covered only a fraction of the area, and prospecting has been confined mainly to the more accessible parts. Placer Mining In late years, dredging or hydraulic mining operations have been responsible for the bulk of production in both the Yukon and Atlin placer gold camps, the operators controlling entire creeks or long stretches of placer ground. Difficulties of access and consequent high transportation costs, combined with the shortness of the mining season, have made it difficult to operate, and have retarded pros- pecting in these fields. Placer miners must get out what gold they can in a short season. The recovery of placer gold represents their only immediate source of income, and they can ill spare the time necessary to a more orderly development of the placer deposits, much less to prospecting for lode deposits. The result is that fair opportunities remain in both worked and unworked creeks, although in many of the former the feverish short-season operating, methods have left workings in such poor condition that . further operations are unprofitable except where dredging is feasible. Nevertheless, opportunities remain for the individual prospector and the chances of making rich discoveries are t seems most likely, however, that future production will come increasingly from hy- draulicking and dredging operations utilizing modern and more efhcient equipment. Many of the placer deposits of northern British Columbia were discovered between 1860 and the end of the century. Their exploitation led, naturally, to further exploration northward, and attention was directed to Yukon. During the years 1896-98, the exceedingly rich Klondike field attracted an unparalleled rush of all sorts and conditions of men from various parts of the world. The greater part of the placer gold that has come from northwest Canada was recovered soon after the discovery of the various fields, many of which, within the space of a few years, rose, flourished, and withered away. During the 1930's, however, systematic exploration and new methods of development were rewarded with success, and placer mining in the region was experiencing a revival of sub- stantial proportions when progress was interrupted by the war. In the summer of 1945, exceptional activity in staking placer leases was reported from the Cariboo and Quesnel mining divisions and from Yukon.