Page:The Journal of geology (IA journalofgeology21894univers).pdf/29

materials, but thus far no petrographer has attempted to study systematically either the field or microscopical relations of any area of these interesting rocks. A very broad and interesting field is thus seen to be awaiting investigation in Newfoundland, Gaspé, New Brunswick, Nova Scotia and the Eastern Townships.

Professor J. B. Jukes, in his "Geology of Newfoundland," describes old lava flows and accompanying pyroclastic deposits as very abundant, especially on the peninsula of Avalon, which forms the eastern part of the island.^[1] His observations are confirmed by the later reports of Murray and Howley, who agree that the western part of this peninsula was the scene of extraordinary volcanic activity in very early times.^[2]

In his three reports on the eastern portion of Cape Breton, Fletcher describes the Ste. Anne, Boisdale, Coxheath, East Bay and Mira Hills, as composed largely of ancient (pre-Cambrian) volcanic rocks, among which felsites of all colors, felsite-porphyries, felsite breccias and amygdaloids abound.^[3] Similar rocks appear also to extend up into, and to form an important part of the Cambrian, Silurian and Devonian formations. In a later report on the northern part of Cape Breton, Fletcher^[4] finds that the greater part of the northern peninsula is also composed of "felsites," but the petrographical distinctions of both Fletcher and Gilpin^[5] are so indefinite that a variety of coarsely crystalline rocks seem to be embraced in this general designation. In describing the Mira "felsites," Fletcher mentions those of Blue Mountain and Gull Cape, near Louisburg, as being "globular," or "concretionary," (coarsely spherulitic?) often presenting "single or united spheroids, the concentric layers of which may