126 A POPULAR EXPOSITION, ETC. 
been found also at the Wallace Mine near the mouth of White 
Fish River, at Echo Lake, Root River, Garden River, Mississagui 
River, Spanish River, and other localities of that region. The ore 
(according to Mr. Murray’s observations) appears to be far more 
abundant in the greenstones than in the quartzites. lLodes of some 
richness in the greenstone, when passing into the latter frequently 
become quite poor. Ottertail Lake, an expansion of the Thessalon 
River, is named by the Geological Survey as a locality from which 
good hones may be obtained. They are cut from the green or greyish 
siliceous slates, found towards the base of the series. From some of 
the soft chloritic slates, also, the Indians have long obtained sufficiently 
compact and sectile masses to be worked into pipe-bowls and other 
objects. 
4, Topographical Distribution :—The Huronian rocks are unknown 
throughout the greater portion of Western Canada, and in the Hast 
they appear to be entirely wanting. The Laurentian rocks of these 
districts, either form the surface of the ground, with or without a 
covering of Drift, or are otherwise overlaid unconformably by Silurian 
strata—the Huronian being absent. The principal Huronian area 
extends along the north coast of Lake Huron from a few miles west of 
French River, where this enters the lake, up to the the neighbourhood 
of Root River opposite the northern part of Sugar Island, or to 
within a short distance of the Sault Ste. Marie. A narrow strip of 
the shore-line, however, from about ten miles north of the entrance 
to Lake George to a point west of Little Lake George, consists 
apparently of newer strata. The extension northward of this Huro- 
nian belt has not yet been definitely made out, but it does not appear . 
to exceed ten or fifteen miles, and in places is less than this. Huronian 
rocks are exposed also at several points on Lake Superior: as in 
Batchehwahnung Bay; at the mouth of the Doré, and around the 
lower part of Michipicoten River; in strips along the coast farther 
west ; and more extensively around the iower part of the Kaminis- 
tiquia River, and elsewhere, on the coast of Thunder Bay. In many 
parts of this region, the Huronian rocks are followed unconformably 
by a somewhat similar series of altered strata, associated with dykes 
and interstratified masses of trap, and containing also, copper ores, 
native copper, and other metallic matters. Until recently, these strata 
were considered to be of Huronian age ; but they are now looked upon 
as altered Silurian deposits, belonging in part to the Potsdam group, 
