Page:The Journal of geology (IA journalofgeology11893univers).pdf/154

Cretaceous.^[1] If the Jurassic exists on the west coast of British Columbia, it must occupy very limited areas or be involved in the pre-Cretaceous metamorphic complex. The fossils collected in the less altered portions of this complex by Richardson and Dawson, show the presence of Triassic and Carboniferous formations, but no undoubted Jurassic forms have yet been detected. It therefore seems that the erosion to which the region was subjected prior to the deposition of the Cretaceous was effected in Jurassic time. As Dawson has shown,^[2] this erosion was of longer duration in the southern part of the province than in the northern, and the transgression of the Cretaceous sedimentation was from north to south.

The further studies of Dawson upon the pre-Cretaceous complex of granite and metamorphics have been fruitful of most interesting and important results. Prior to his researches the granite (and granite-gneisses) of the region were generally regarded as the equivalent of the Laurentian of the east. It was shown,^[3] however, by him that the basement upon which the now metamorphic sedimentary and volcanic strata of the Vancouver series (Triassic, with probably some Carboniferous), was deposited is non-existent, and has been replaced by an immense mass of intrusive granite, which has absorbed by fusion all rocks below the present remnants of the Vancouver series, and has invaded the latter after the manner of an irruptive magma. This post-Triassic granitic batholite is of enormous dimensions. In the fall of 1890 the writer had an opportunity of examining it cursorily for a distance in a straight line of over five hundred miles, in and out of the fiords of the coast from Burrard Inlet to Alaska; and the granite is known to extend far northward into that territory. Its width may be placed at from sixty to one