238 AGE OF CONGLOMERATE CAPPING THE 



No detailed consideration has been given to this basal deposit 

 in the writings of Dawson and Belt or in the reports of Professor 

 Bailey and Mr. Faribault for the Geological Survey of Canada, 

 and the only paper we have had bearing more than superficially 

 on the matter is one by Mr. W, H. Prest on the Glacial Succes- 

 sion of Central Lunenburg; a paper that shows careful examina- 

 tion of certain deposits met with in the actual course of pros- 

 pecting for gold leads under the guidance of experience and a 

 study of the latest literature on glacial pli^^nomena. 



Mr. Prest correlates the Halifax rock with the Bridgewater 

 conglomerate which he classes as the most ancient, one that 

 formerly masked a large part of the province, covering the 

 country to a considerable depth, as in the LaHave valley he 

 found it from sea level to two hundred feet above it. It is always 

 in contact and cemented to the bed-rock and almost immovable 

 without the aid of dynamite, and yet in spite of its extreme 

 hardness, it has been excessively divided and now is left only 

 in patches. In origin as glacial, he considers " the presence of 

 striated boulders testifies with no little weight, and from a 

 northern source proved by its contents, which consist of slate 

 from near by, quartzite from the northwest, granite from the 

 central watershed, diorite from the south side of the Annapolis 

 valley and trap from near the Bay of Fundy. In no more 

 striking manner can its immense relative antiquity be illustrated 

 than by comparing its highly oxidized condition with that of 

 the overlying till.' 



So far no deposit of this character has been detected near 

 Halifax to rest on the granite intrusions, and this, perhaps, is 

 not a matter of surprise, for the binding material that cements 

 the stones together is iron oxide, evidently derived from the 

 decomposition of pyrite which is prevalent in much of the 

 graphitic strata. Indeed it is considered by the stone workers 

 of the place that a similar action is now going on where trickles 

 of water pass rusty from nodules of pyrite. The binding 

 together of the coarse material composing the conglomerate in 



