25 PROTEROZOIC AND (?) LATER Peace River Valley _ The oldest rocks recorded from Peace River Valley are the Misin- chinka schists, first observed by Selwyn in 1875 and later named by Dawson (1881). They consist of finely laminated, pale, silvery mica schists, and are exposed in Peace River Valley from Andy Creek to Finlay Forks. They are unfossiliferous, and have been referred tentatively to the Precambrian (Williams and Bocock, 1932). Finlay River Valley Rocks resembling those of the Misinchinka schists and possibly continuous with them outcrop on both sides of Finlay River Valley. They consist of “mainly quartz-mica schist, mica quartzite, and acid gneiss, but there are also a few small bands of impure limestone and lenses of horn- blende gneiss” (Dolmage, 1928). Some of these metamorphic rocks may prove to be of Cambrian age (See Roots, 1948). Toad River Valley The fossiliferous Silurian strata along the Alaska Highway in the Rocky Mountains are underlain unconformably by two rock groups, one more metamorphosed and more folded than the other (Williams, 1944; Laudon and Chronic, 1947). One has been referred, tentatively, to the Precambrian and the other, provisionally, to the Cambrian. The older group is exposed on Toad River near the highway crossing and southeast of the bridge over McDonnell Creek. Williams states that it consists of metamorphosed, light-coloured quartzites, porcellaneous argillites, and slaty rocks with ripple-marks and mud-cracks. Laudon and Chronic (1949) record quartzite, schist, slate, and marble. These rocks are intruded by dykes of diabase and quartz gabbro, the only known igneous rocks in the region. Where they are in contact with Silurian strata Williams considers the relation to be that of an angular unconformity. CAMBRIAN ? Peace River Valley Alfred R. C. Selwyn, during an exploratory traverse of Peace River, in 1875, ascended a conspicuous peak of the Rocky Mountains, on the south side of the river below Finlay Forks, which Macoun, who accompanied him, named Mount Selwyn. He observed massive quartzites on the lower ridges of this mountain. Williams and Bocock incorporate these beds into what they call the Mount Selwyn formation, which they state consists of about 3,500 feet of buff-coloured, massive quartzite and pink, calcareous shale. ‘They compare the beds of this formation with Cambrian quartzites in the southern Rocky Mountains, and suggest that they may be of Cam- brian age. They also note that this formation is present in the Murray Range at the summit of Pine Pass. East of Finlay River Valley Dolmage (1928) has mapped a wide band of white and grey, unfossili- ferous limestone, partly pure, partly argillaceous or arenaceous, in the Rocky Mountains, east of Finlay Valley. He calls them “Cambrian (?) and possibly younger” because McConnell (1897) “considered them to be a 60920—34