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inated with, and cutting across the bedding of the Huronian rocks; the absence of sedimentary rocks within the gneiss, and the general character of the gneiss, which in appearance and behavior more nearly resembles an eruptive granite than an altered sedimentary rock. It is therefore concluded that the Huronian is the oldest series of sedimentary strata in this region, and that the floor upon which these were lain down must have been subsequently fused and recrystallized.

Comments.—That in many localities there are granites and gneissoid granites intrusive in the Huronian of Lake Huron has been well known since the days of Logan. However, because a part of the granites are intrusives later than the Huronian, this does not show that the basement upon which the Huronian was laid down does not still exist, in part at least, as held by Logan, Irving, Pumpelly, and others. The account of the facts and their interpretation at the contacts near Thessalon by Barlow are so irreconcilable with those given by Pumpelly, Irving, and myself, that the former or the three latter must have wholly failed to grasp the truth. These latter hold that there is here the most manifest evidence of profound unconformity between the Basement Complex and the Huronian. Should this position prove correct, the question would naturally arise as to what extent the accounts of the remaining localities described by Barlow need revision.

Smith,^[1] in 1893, gives a general description of the Archean rocks in the southern half of the Rainy Lake district in the Province of Ontario, between the Thunder Bay district and the Lake of the Woods. The rocks here found are divided into the Lower Archean and Upper Archean, the term Archean being defined to include all pre-Cambrian rocks. The Lower Archean series, or Laurentian, comprises a lower granitic and syenitic division, and an upper micaceous, hornblendic and trappean division, for the most part schistose. The first usually occurs in rounded or ovoid areas, between which are the rocks of the Upper Archean or Ontarian.

The Ontarian system includes the Contchiching and Keewatin series. The Contchiching rocks are mainly mica-schists, and have an estimated thickness of 9,000 feet, the apparent thickness of 24,000 to 29,000 feet, given by Dr. Lawson, being believed to be due to multiple folds. These mica-schists are regarded as clastic in origin, because of their fine and even lamination. The Keewatin consists for the most part of plutonic, volcanic, and pyroclastic rocks, although in some of the upper members there are more or less aqueous sediments. The Contchiching and Keewatin are everywhere in strict conformity, although at the base of the Keewatin in certain localities there are conglomerates regarded as local and volcanic.