312 H. S. POOLE ON- THE GOLD-LEADS OP NOVA SCOTIA. 



and fragments of quartzite may be found imbedded in it. That the 

 intense heat of the granitic mass aifected the structure of the con- 

 tiguous strata is evident from the development of andalusite crystals 

 in the quartzite, and of garnets in the slates, — the former at Moose- 

 land and near Pifteen-Mile Stream; and the latter close to the gra- 

 nite of Cochran's Hill, Sherbrooke, in the walls of gold-leads, and 

 even imbedded in the quartz itself. 



A most interesting spot bearing on the subject of this note is on 

 the barrens near the west shore of Moose Lake, where a quartz-lead 

 rising somewhat above the level of the containing quartzite is capped 

 by granite and pierced by small tongues of granite, suggestive, if not 

 conclusive, that the leads are of greater age than the granite. 



Glaciation and the Leads. 



Grooves and striae on the surface of the rocks protected from 

 further action by a covering of earth are common throughout the 

 region. Glaciers, an ice-sheet, and icebergs have each their advo- 

 cates to account for them ; and the amount of denudation that they 

 have occasioned is variously estimated. The labours of the gold- 

 prospector have supplied some data which should not be overlooked 

 in forming a conclusion on the subject. The experience of the 

 gold-miner leads him, when he finds the " throw " of a vein, as he 

 calls the float or shoadstones, to seek to the northward. He gene- 

 rally expects to find it within 100 feet of where the "throw" 

 comes to the surface — on the hang of a hill, and where the cover is 

 heavy, at a greater distance than where the surface is flat and the 

 soil thin. In exceptional cases, where a rich throw has been found, 

 trenches have been dug for many hundreds of feet, and every inch 

 of the ground examined without discovering the lead. The so-called 

 Eose lead at Montagu is still unknown, though the throw or drift 

 of similar appearance, and supposed to have come from one lead, has 

 been found to extend over 1000 feet of ground*. Another instance 

 occurred this summer (1878) at Cariboo : large boulders of quartz, 

 weighing in aU some 40 tons, which were obtained from one spot, 

 yielded largely, and great search was made for the lead from which 

 they had been derived ; but the exploring- trenches both to the north 

 and south failed to find a lead. The boulders were found resting on 

 the bed-rock, which at the particular spot where they were found 

 was on a level with the surface, while about it the surface-soil was 

 deep. 



Boulders of other rocks have been traced to their source miles 

 away. In the neighbourhood of Halifax the drift contains frag- 

 ments of limestone from the Lower Carboniferous and of amygda- 

 loidal trap from the Triassic of the Bay of Pundy, some sixty miles 

 distant. A lump of iron-ore was found on digging a well at Ham- 

 mond's Plains, of similar appearance and composition to that of the 

 nearest known ore, that of Brookfield, thirty miles to the north. 

 These instances are sufiicient to show that while the drift has carried 



* Since traced 2200 feet in the direction of the striae, and a rich mine opened. 



