DEVELOPMENTS IN PRE-CAMBRIAN STRATIGRAPHY 391 
between Lake Savant and Lost Lake, in the Lake of the Woods 
and Rainy Lake districts,2 in the Vermilion district,3 and at 
Steep Rock Lake,‘ it has been found that highly metamorphosed 
conglomerates, slates and schists of sedimentary origin occur in 
association with the volcanics and, as in the pre-Cobalt series 
complex of the Timiskaming region, the conglomerate although 
intruded by granite contains granite pebbles. But in only two 
localities—the Vermilion district and Steep Rock Lake—has the 
conglomerate been found resting unconformably on the surface 
of the older granite from which its pebbles were derived. 
Here and there this basement complex is overlain by two series 
of almost flat-lying sediments, the older of which is known as 
Animikie and the younger as Keweenawan. In some places, as 
on the shore of Thunder Bay, both series are present; but in others 
the Animikie occurs alone, or the Animikie is absent and the 
Keweenawan rests directly on the surface of the complex. 
The names which have been applied to the various formations 
composing the (pre-Animikie) complex found in the region north 
and west of Lake Superior, have varied in different localities 
and at different times. For many years following the work of 
Logan and Murray on the north shore of Lake Huron, the geologists 
who investigated these pre-Cambrian terranes, with but one notable 
exception, called the granite and gneiss Laurentian and the vol- 
canic complex Huronian. But A. C. Lawson who reported on the 
geology of the Lake of the Woods and Rainy Lake regions for the 
Canadian Geological Survey, departed from the general custom 
and adopted a local nomenclature. According to Lawson’s classi- 
fication the granite and gneiss were Laurentian, but the volcanics 
and sediments were grouped into an Ontarian system which had 
two divisions, the Coutchiching series, largely composed of sedi- 
mentary mica schist and the Keewatin, consisting for the most part 
of volcanics. In the Vermilion district of Minnesota, where much 
detailed geological work has been carried on since Lawson’s reports 
t National Transcontinental Railway between Lake Nipigon and Clay Lake (Geol. 
Surv. Dept. of Mines, Can.), 1909; Ann. Rep. Ont. Bur. of Mines, 1910. 
2 Ann. Rep. G.S.C., 1, Part CC, 1885; zbid., III, Part F, 1887-88. 
3U.S.G.S. Mon., XLV, 1903; ibid., Vol. LII, ort. 
4 Memoir No. 28 (G.S. Dept. of Mines, Can.), 1912. 
