Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/659

 which in New Brunswick and Nova Scotia preserve a remarkable parallelism. These corrugations, in the descriptions of the structure of the Nova-Scotian gold-districts, arc termed the cast and west anticlinals*.

VI. Relation of the Gold-Districts to the Gneissic Areas.

The north and south anticlinals are low broad undulations which have ridged the country (Nova Scotia) in a nearly meridional course. At the intersection of the north and south with the cast and west anticlinals, the gold-districts of Nova Scotia are situated; and it is here also that denudation has occasionally exposed the gneissic rocks in patches, like islands in a Silurian sea.

The map of the gneissic rocks in the county of Guysborough, Nova Scotia (fig. 4), is an illustration of this form of outcrop ; and the map showing the Silurian valley between Halifax and Windsor (the Atlantic and the Bay of Fundy) exhibits the protecting influence of the north and south synclinals (fig. 1).

Where islands of gneiss occur in Nova Scotia, the gold- districts are symmetrically arranged around them — the outcrop of the lodes (which are beds of quartz) having a semielliptical form, the base of the ellipse resting on the gneiss.

Where they occur in a Silurian valley, between great exposures of gneiss, as represented on the map showing the structure from Halifax to Windsor (fig. 1), the exposed edges of the beds of quartz have also a semielliptical form ; and if two districts are situated on opposite sides of the valley, the apices of the semiellipses point towards each other, their bases resting on the gneiss, as in the case of Waverley and Mount Uniacke.

Where denudation has not reached the gneiss, the outcrop of the bedded lodes may have any of the symmetrical forms which can be produced by the intersection of plane and curved surfaces.

Prom the uniform distribution of the auriferous beds of quartz in the Silurian rocks of Nova Scotia, we may expect to find accessible deposits at the intersection of the anticlinals all over the Province, where they are not concealed by superior formations; and since denudation has taken place to the greatest extent near gneissic areas, it may be anticipated that the correct mapping of these rocks will be of considerable economic advantage to the Province.

Recent operations in the gold-district of Waverley have afforded very satisfactory proofs of the contemporaneous bedded structure of many of the Nova-Scotian lodes, and also of the general structure assigned to the districts, and of their occurrence at the intersection of cross anticlinals as well shown in the case of the recovered Tudor and North Lodes at Waverley, and in the districts of Waverley and Sherbrooke generally, winch are types of all the known gold-districts of Nova Scotia.

These proofs are thus referred to by the Chief Commissioner of

Author.
 * Sec ' Reports on the Waverley and Sherbrooke Gold-Districts,' by the