CAPE BKETOX ISLAND, ISTOVA SCOTIA. 521 



cases no divisional line can be drawn separating the Millstone Grit in 

 its passage upwards from the Productive Measures, or downwards 

 from the limestone series. The most instructive section is that at 

 the Joggins, in Cumberland county, Nova Scotia, where all the sub- 

 ordinate formations are fully developed. 



In several cases in Cape Breton the gradual passage of the sub- 

 divisions is strongly marked. In this island the arrangement of 

 this formation isr that of valleys between the ridges of the Pre- 

 Cambrian hills, and their softer strata have been worn into broad 

 river-valleys and rolling hills of inconsiderable altitude. When 

 they rest on the flanks of the older hiUs, they present picturesque 

 and charming gorges, worn by the brooks, which are long fed by 

 the accumulated winter snows. 



As the eastern district is the most typically developed, a brief 

 description of it will answer for the central and northern ones, 

 which resemble it in the physical characters of the rocks, and differ 

 from it chiefly in the correlation of the subdivisions. 



In the Sydney, or eastern district, as in the remainder of the 

 island, the upper division is wanting, unless represented by a few 

 beds at Low Point, and some of the upper beds of the Hiver-Inhabi- 

 tants district. The shore, from Cape Dauphin to Mira Bay, is occu- 

 pied by the Productive or Middle Coal-measures, which are folded 

 in three undulations having an east and west axis, corresponding 

 to that of the Pre-Cambrian strata. As the measures are inter- 

 rupted at the anticlines, the exact identification of all the seams is 

 doubtful. 



The following section in the Lingan district, in the centre of the 

 field, will serve to show the relative thickness of the strata and of 

 the included beds of coal : — 



ft. in. 



Seam A 3 



Strata 306 2 



Carr seam 6 5 



Strata ..5. 191 



Barasois seam 12 



Strata 379 3 



David Head seam 8 



Strata 235 



SeamD 3 



Strata 78 



North Head seam 4 



Strata 76 



Lingan Main seam ... 8 



Strata 95 3 



Seam a 2 6 



Strata 340 5 



SeamH 1 



This section does not embrace lower coal-seams of workable di- 

 mensions included in the Millstone Grit of the Geological Survey. 



Shales, arenaceous and argillaceous, with red and green marls, 

 make up one half of the strata. The shales pass into sandstones, 

 and frequently carry ironstone nodules ; and the more argillaceous 

 beds are crowded with fossils, chiefly ferns. Many trunks of erect 



