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Keweenawan by Irving, and the Bohemian Mountains of Keweenaw Point. It is suggested that the anorthosites of Lawson are but facies of the gabbro, and that the two belong together in the Norian.

Comments:—This paper correlates with the so-called Norian of the East the gabbros and similar rocks of the Lake Superior region, which have heretofore been considered as constituting a part of the Keweenawan. Such lithological correlations are believed to retard, rather than advance geological progress, as they rest wholly upon unverified assumptions. The local name Keweenawan ought to be retained for the gabbros and allied rocks, or else some new local name ought to be devised for it. This latter is done by Lawson as appears from the paper next summarized.

Lawson^[1] gives a petrographical and structural account of the anorthosites of the Northwest shore of Lake Superior. The anorthosite is wholly massive, completely granitic in structure, and is composed almost wholly of basic feldspar, varying in composition from labradorite to anorthite. The rock occurs near Encampment Island, in the vicinity of Split Rock point, at Beaver Bay and vicinity, at Baptism river, on the slopes of Saw Teeth mountain, and at Carlton Peak. In nearly all of these localities the rock is found in rounded dome shaped masses below the other eruptives of the coast. It is cut by these different eruptives, and in the lava flows are found very numerous blocks and bowlders of anorthosite, which were caught in at the time of their extrusion. These facts show that the anorthosite is of pre-Keweenian age, and since the anorthosite is a plutonic rock, it must have suffered profound erosion prior to the extravasation of the Keweenian eruptives. Norwood, Irving and Winchell have described the blocks of anorthosite in the lavas at some of the points. Winchell regarded the anorthosite at Split Rock as older than the eruptives containing masses of them, and Irving reached the same conclusion in reference to the anorthosite at Carlton Peak. However, none of them differentiated the anorthosite mass from the general aggregation of volcanic flows, constituting the Keweenian series of the Minnesota coast. The surface of the pre-Keweenian anorthosite is domed and hummocky like that of the other Archean terrains of Canada, and it is thought to have been only modified by Pleistocene erosion. The interval between the anorthosite and the Keweenian is probably the same as the pre-Paleozoic interval which effected the reduction of the Archean to the great hummocky plain, to which it was reduced before the Animikie was deposited upon it. As the Keweenian rests directly upon the anorthosite, the Animikie is absent for the middle third of the Minnesota coast. Irving places the thickness of the Keweenian of the area at 20,000 feet, stating that it may reach 22,000 or 24,000 feet. The maximum thickness of the