•2±G Williams— Geology of Arisaiy-Antigonish District. 



I '/per Cambrian deposits. — The oldest rocks known in the 

 district are metamorphosed graywacke and slate of the Brown's 

 Mountain group, which underlie the plateau areas and form 

 the hase for the younger formations. All of the younger sedi- 

 ments at one place or another rest directly upon the metamor- 

 phic rocks. The Brown's Mountain group may be divided 

 iithologically into two divisions, — a thick lower formation of 

 silicified graywacke, impure quartzite and gray handed slate 

 known as the James River formation; and an upper division 

 of crumpled red slate with some sandstone and schist, known 

 as the Baxter's Brook formation. Oolitic hematite beds are 

 found in the James River rocks near the base of the Baxter's 

 Brook division and again at a lower horizon. The sedimentary 

 origin of the iron ore is most probable from the consideration 

 of the oolitic and sparingly fossiliferous character of the ore, 

 its longitudinal extent, and its close association with definite 

 rock horizons.* Some secondary concentration or transference 

 of material may, however, have taken place. 



So far as could be observed, the two formations have entirely 

 conformable relations to each other, and on the evidence of 

 Obolus (Lingulobolus) spissus and Lingulclla (?) obtained from 

 the upper iron-ore horizon (both from the ore itself and the 

 associated schist), these rocks are proven to be of Upper Cam- 

 brian or Ozarkic age. The iron ore is likewise correlated with 

 the Wabana ore of Belle Isle, Conception Bay, Newfoundland ; 

 but because of low grade and faulted condition it has not yet 

 been commercially developed, although portions of it will prob- 

 ably be profitably mined sooner or later. 



The characters of the Brown's Mountain sediments are 

 thought to indicate that they were deposited in a shallow 

 transgressing sea; the upper red slates were formed, perhaps, 

 by the inwash of fine oxidized sediments from a land already 

 reduced to moderate relief. 



The present structure of the Upper Cambrian rocks consists 

 of broad folds extending in a northeast direction, crossed by a 

 few closed northwest secondary folds. The upper red slates 

 are also intimately crumpled and folded as a result of the many 

 intrusive bodies which have penetrated them. 



\ Ordovician deposits. — Erosion agencies appear to have worn 

 wide channels out of the Brown's Mountain rocks before the 

 later sedimentary formations were laid down. The coarse cross- 

 bedded conglomerates and grits of the Malignant Cove forma- 

 tion, occurring at Malignant Cove and to the south, were 

 deposited upon the cleavage surfaces of the James River slates. 

 Their deposition was evidently influenced by strong current 



* For particulars see Woodman, J. E.. Canada. Dept. Mines, Mines Branch, 

 Eeport on Iron Ore Deposits of Nova Scotia, Pt. I, 1909. 



