330 MINERALS AND GEOLOGY 



general dip being in the latter direction. They comprise a slight 

 development of Huronian quartzites, with representatives of the 

 Chazy, Black River and Trenton, Utica, Hudson River, Clinton, 

 Niagara, and Guelph formations. The Huronian outcrops occur 

 principally *in the form of bare, rocky ledges, but are only seen at 

 one or two places, principally at Shequenandod village, near the 

 eastern extremity of the Great Manitoulin, on La Cloche Island, and 

 on the Island of Campement d'Ours, near the entrance to St. Mary's 

 River. Exposures of reddish marls and light-coloured sandstones on 

 the north side of La Cloche Island are commonly referred to the 

 Chazy division ; and the thin bedded sandstones (provisionally 

 known as the Ste. Marie sandstones), which occur in small outlying 

 patches on Campement d'Ours and St. Joseph's Island, are thought, as 

 regards their geological positon to represent the same formation. The 

 southern portions of La Cloche Island, and the smaller islets imme- 

 diately west, are occupied entirely, or essentially, by dark gray 

 dolomitic limestones of the lower part of the Trenton (or so-called 

 Black River) series the higher beds merging into the Trenton 

 division proper, and supporting at one or two points small strips or 

 patches of Utica shale. The Bigsby, Thessalon, and other rocky 

 islands farther west, and a large part of Campement d'Ours and St. 

 Joseph's Island, belong to the same series. From the La Cloche 

 group of islands these Trenton strata extend across the intervening 

 channel, and crop out in several places as a fringe along the north 

 coast of the Great Manitoulin. They show principally in the Mani- 

 towaning headland, and also between Little Current and West Bay. 

 Southwards, the dark bituminous shales of the Utica formation come 

 up, and range entirely through the islands. Good exposures occur 

 at Shequenandod village (where the shales incline against an outcrop 

 of Huronian quartzite), and ac Cape Smyth. At the latter spot the 

 formation is capped by a considerable thickness cf arenaceous shales 

 and sandstones, very rich in fossils, belonging to the Hudson River 

 series. This latter formation ranges also entirely through the Great 

 Manitoulin, and extends over Barrie Island on the north. It is fol- 

 lowed along its southern border by a series of strata holding Clinton 

 fossils. These strata consist mostly of light-coloured dolomites capped 

 by a bed of red marl the best soil on the island, according to Dr. 

 Bell, resulting from the disintegration of the latter. South of these 



