Papers read at the British Association at Montreal. 467 



represents about 100 miles of surface previously to the 

 crumpling of the crust and elevation of the mountains. 



7. This result, for several reasons, below rather than above 



the truth. 



8. Geographical effects of this contraction. 



9. Development of the fact that such elevation of mountains by 



tangential pressure involves not only elevation, but con- 

 siderable horizontal movement. 



10. Diminution of motion to north-west. 



11. A few words on the failure of attempts yet made to account 



for this contraction. 



12. Suggestions and conclusions. 



2. — A Comparison of the Distinctive Features of Nova-Scotian 



Coal-fields. 



By Edwin Gilpin, Jun., A.M., F.G.S., F.R.S.C. ; 



Government Inspector of Mines, Province of Nova Scotia. 



rr^HE Carboniferous rocks of Nova Scotia cover a large part of the 

 X northern side of the pi'ovince, and are exposed in unusually 

 good sections. The presence of workable Coal-seams has led to 

 many surveys, etc., which have resulted in a good knowledge of their 

 structure. The best known and most continuous sections are those 

 of the Joggins in Cumberland county, and of the Cape Breton Coal- 

 fields. There are numerous Coal-fields, the most important being 

 those of Cumberland, Pictou, and Cape Breton. 



The presence of east and west synclinal folds is noticeable in each 

 of these districts. In the Sydney Coal- field these foldings are on the 

 prolongation of the ranges of the Pre-Carboniferous rocks, and die 

 oat as they recede from them. In all these Coal-fields these flexures 

 are not accompanied by serious faults, except where the older 

 measures have interrupted or complicated them. Thus on the north 

 side of the Cumberland Coal-field the measures are comparatively 

 free from disturbances where no Pre-Carboniferous strata appear, 

 while numerous dislocations are found on the south side, where they 

 rest almost directly on the Silurian slates of the Cobequid mountains. 



In the Sydney Coal-field the sections show the ancient centre of 

 the Coal-field where the maximum of coal and the minimum of 

 strata occur, from which it would appear that the distributing 

 currents carried material principally from the north and the south ; 

 the source of part of the detritus being the bordering Lower 

 Carboniferous strata. The slight difference of deposition, however, 

 is marked by the presence of beds of bituminous and fossiliferous 

 limestone, which, chiefly developed in the centre, extend almost from 

 end to end of the district. 



In the Pictou district a noticeable point is a horizon in the lower 

 part of the section containing 1500 feet of shale, and coal in beds 

 up to 38 feet in thickness. This curious formation is referred 

 to the presence of a contemporaneous barrier-reef of shingle formed 

 from the Millstone Grit, and allowing under its shelter an immense 

 accumulation of argillaceous and carbonaceous sediment. lu the 



