34 THE PERMO-CAKBOXIFEROUS. 



pliic rocks on the eastward and southward to a line running nearly 

 east and west through the town of New Glasgow, consists entirely of 

 the Lower Carboniferous, Millstone-grit, and Middle Coal formation, 

 and contains all the known workable Coal-measures of the county. 

 Its northern boundary, the New Glasgow anticlinal, brings up a bed 

 not recognised in the other Nova Scotia Coal-fields — the New Glasgow 

 Conglomerate, an immense mass, believed in some parts to be 1600 

 feet in thickness,* and containing boulders 3 feet in diameter, with 

 pebbles of all sizes, many of its largest stones being composed of the 

 hard brown or purplish sandstones of the Lower Carboniferous. Its 

 stratigraphical position is that of the upper part of the Millstone-grit or 

 lower part of the Middle Coal formation; and it is evidently an excep- 

 tional bed, representing an immense bar or beach of gravel and stones, 

 stretching from the eastern end of the inetamorphic chain of the Cobe- 

 quid Mountains across the Pictou Coal-field, and protecting those deep 

 swamps in which the Pictou nnvin coal, 36 feet thick, and its black shale 

 roof, more than 1000 feet thick, were deposited. The theory of this 

 remarkable deposit, one of the most singular connected with any coal- 

 field, is fully discussed in the second edition of my "Acadian 

 Geology." I may merely remark that, facing, as this bed does, the 

 open sea stretching to the northward in the Coal formation period, it 

 is not unreasonable to suppose that it indicates the action of heavy 

 ice grounding on the shores behind which grew the Sigillaria forests 

 of the Coal-swamps. The arrangement of the beds in the first syn- 

 clinal, which is that of the great Pictou Coal-beds, has recently been 

 worked out in much detail by Sir W. E. Logan and the late Mr E. 

 Hartley. 



The Secoiul or middle synclinal extends from New Glasgow to 

 Carribou Harbour, and centres in the deep indentation of Pictou 

 Harbour. On its southern side it contains, north of New Glasgow, 

 the depauperated equivalent of the Middle Coal formation ; and the 

 remainder of it is occupied by the Newer Coal formation, whose 

 newest beds, however, are not represented in this trough. The low 

 anticlinal which separates it from the third trough brings up nothing 

 older than the lower part of the Newer Coal formation. 



The Third synclinal extends from Carribou Hai'bour to Cape John, 

 and, stretching Avestward through the Cumberland Coal-field, shows 

 in its centre the newest beds of the Upper Coal formation, here more 

 especially referred to. 



It is to be observed that in these synclinals the north-west sides 



* This is Sir \V. Logan's estimate, and is warranted by the breadth which the bed 

 occupies in the section ; but there are indications that it thins rapidly toward tlie dip. 



