AREA.
The area of the Arcadian coal-fields is very extensive, and has been variously estimated from 5000 to 10,000 square miles. The total area is perhaps not less than 9000 square miles of coal measures ; but we have hesitated to accept 2500 square miles as productive, since the large or work able seams cover but a comparatively small limit, while the underlying and unproductive seams exist over a wide extent of territory. The large upper seams have not been found in any but the Pictou basins. In Cum berland, at the Joggins, the third series of coal-seams appears to produce all the workable coal, which exists in the following order:— The thickest bed among these 78 seams is only 4 feet 6 inches in diame ter, and contains only 3 feet 8 inches of coal ; while only two or three of the remainder contain more than 2 feet of workable coal ; and since these seams are measured where exposed on a high bluff against the Bay of Fundy, or the Chignecto Bay thereof, where much of the original out crops must have been swept away by the waters, and thus exposing the coal-beds in their maximum condition, we may expect these seams to de preciate as they descend under the deeper parts of this deep Cumberland basin. It is not likely, therefore, that these seams will ever be very pro ductive ; and, since the same lower measures exist exclusively in New Brunswick, and perhaps in Prince Edward's Island and Newfoundland, these coal districts can never be considered productive to any extent.
The coal districts of the "Joggins," in Cumberland, and a correspond ing horizon throughout this county, may produce coal for local demand, but little for exportation. The same may be said of the coals of New Bruns wick, Prince Edward's Island, Newfoundland, the eastern extremity of Nova Scotia, and the southwestern end of Cape Breton Island. The only productive districts are those of Pictou in Nova Scotia and Sidney in Cape Breton Island ; and we think our estimate of 2500 square miles quite as extensive as the productive area.
The coal-seams of Sidney, in Cape Breton Island, are of moderate dimensions. They may be thus enumerated :— The Arcadian coal-fields in the British Provinces are divided by geo logists into a number of districts or basins ; but each district (as the Pictou) may be divided into several basins, in which the coal-seams undu late without coming to the surface, or they outcrop and the basins are divided by the Mountain or Carboniferous limestone, or the metamorphic and Plutonic rocks. The basins, however, are wide and deep, and the dip
of the strata is gradual and uniform,—seldom over 20° in inclination, and generally much below.
These basins were not formed, as most of our Eastern basins are, on the sandstones which fill or prepare them for the coal measures, but are formed on the early limestones which succeeded the Potsdam sandstone and the gneissic period ; and the succeeding limestones which fill our Western basins also make up the greatest portion of the measures in these. But perhaps there are more shales, slates, clays, and sandstones here than in the West, as these basins are deeper than the Western basins, and perhaps sub ject to more drift and debris from the higher grounds which surrounded them and from the great river which flowed into them. They were deeper than our Western basins ; and, since all appear to have been filled nearly to the brim, of course the deepest basins retained or held the greatest amount of sediment.
The amount of sulphur and iron pyrites in the measures and seams of the Arcadian fields is of serious injury to the value of the coal. We may account for its existence as a creation from sublimation ; and since sulphur and iron pyrites exist in greatest profusion in the vicinity of the gneissic formation, and, consequently, in all coal-fields, stratified on or in the gneiss, or in proximity to it, we may account not only for the sul phur, but the sulphate of lime, or gypsum, which exists so plentifully in the Arcadian coal-measures, on the same principle, from the absence of the intervening masses of sedimentary sandstones which accompany all our great coal formations, except the Western. Most of the coals of Arcadia are of the fat or highly bituminous order, and plainly indicate their remote ness from the regions of the great heat which operated on the Pennsyl vania anthracites.