130 THE CANADIAN NATURALIST. [Vol. vii. 



Silurian age, in the Lower Carboniferous, and at the junction of 

 these two groups of rocks. We may shortly consider the deposits 

 of these several kinds and ages in their order. 



1. Bedded Ores. 

 (1) Great Hematite Bed of the Lower Ilelderherg Series. 



This, in so far as at present known, is most extensively de- 

 yeloped in the vicinity of the East Branch of the East River of 

 Pictou, and on the upper part of Sutherland's lliver. Here the 

 rocks which rise unconformably from beneath the Carboniferous 

 beds of the Pictou coal-field, consist in great part of gray and 

 olive slates, usually coarse and unevenly bedded, and with 

 occasional calcareous bands, holdino; the characteristic fossils of 

 the " Arisaig group," a series in Nova Scotia equivalent to the 

 Lower Helderberg of American geologists, though in its specific 

 forms more nearly allied to the English Ludlow than to groups 

 of this age on the great inland plateau of America. These beds 

 are affected with sh^ty cleavages, highly inclined, much faulted, 

 and folded in abrupt anticlinals, so that their detailed arrange- 

 ment has not yet been satisfactorily traced. The great ore-band 

 which forms one of the most conspicuous marks for unravelling 

 their complexities, has been traced mainly along two distinct 

 lines of outcrop, both somewhat curved and broken, and which 

 seem to lie on the opposite sides of an anticlinal axis. It has 

 also been recognized in two other localities where it must come 

 up on distinct lines of outcrop, the precise relation of which to 

 the others has not yet been ascertained. 



The ore bed is accompanied by a thick band of olivaceous 

 slates, and beneath this there appears hard ferruginous quartzite 

 which Dr. Honeyman compares to the Medina sandstone. Lower 

 than this and possibly unconformable to it are black and green- 

 ish slates with bands of quartzite and soft chloritic and nacreous 

 schists which as yet have afibrded no fossils. They are associated 

 with hard beds or masses of rock rising into some of the highest 

 eminences, and which have usually been described as trap, but 

 which seem to consist for the most part of an indurated slaty 

 breccia or conglomerate, corresponding very nearly in character 

 to the typical graywacke of the older German geologists. These 

 rocks may be of middle Silurian age. though possibly in part 

 older, and we shall meet with them again in connection with the 

 great vein of specular iron. 



