7(5 



THE UPPER SILURIAN". 



Farther eastward, at French River and AVaugh's River, the repre- 

 sentatives of the "Wentworth series contain coarse limestone and 

 hard sandstone as well as shale, but hold some of the same fossils, 

 and at Earlton loose pieces contain fossils of a somewhat higher 

 horizon equivalent to the Upper Arisaig series. 



Passing from the eastern end of the Cobequids across a bay of the 

 Pictou Carboniferous area, we find well-characterized Upper Silurian 

 rocks with fossils of the Upper Arisaig (Lower Helderberg) age. 

 These rocks have recently been somewhat carefully examined in 

 connexion with explorations of the great deposits of iron ore asso- 

 ciated with them. It would seem that the upper half of the Upper 

 Silurian is here quite as well developed as at Arisaig, and includes 

 the great bed of fossiliferous hematite which is so characteristic of this 

 region (Fig. 13). From below these beds arise thick beds of ferru- 



Fig. 13.— Ideal Section, showing the general relations of the Iron Ores of the East 



River of Pictou. 



M^^&mJz 



a 



1. Great bed of Red Hematite. 



2. Vein of Specular Iron. 



3. Vein of Limonite. 



(a) Older Slate and Quartzite series, with Ftdsite and Ash Rocks, etc. 

 (J) Lower Helderberg formation and other Upper Silurian Rocks, 

 (c) Lower Carboniferous of the East Branch of East River. 



ginous quartzite, and of imperfectly crystalline diorite and slaty and fel- 

 sitic breccias, which would seem to be lower members of the Upper 

 Silurian, and which are less indurated than the rocks of similar composi- 

 tion referred to the Lower Silurian and older series in the sequel. These 

 latter rocks, which also appear in the vicinity of the Fast River, are 

 breccia, felsite, quartzite, slates, and hydro-mica schists, which bear a 

 close resemblance to the Cobequid series, and pass to the southward 

 and westward of the newer rocks, no doubt forming in this region 

 the continuation of that formation. In the central parts of the hills, 

 at the head-waters of the East River, these beds are seen, as in the 

 Cobequids, to be invaded by great masses of an intrusive red syenite. 

 Eastward of the East River the continuation of the Upper Silurian 

 rocks has been traced by I)r Honeyman all the way to Arisaig, 

 where their characteristics are fully described in Acadian Geology ; 

 and beyond this as far as Lochaber Lake, where at least the lower 

 members occur. 



