244 



Bunbury and Dawson was mainly collected by Brown, 

 chiefly from the North Sydney area and in no small part 

 from one shale bed overlying the Main seam. From this 

 single horizon, it is stated by Brown, that over 90 plant 

 species were obtained. 



The Carboniferous strata of the district have been 

 grouped and mapped under four divisions of which the 

 highest, the Productive Coal Measures, embraces the 

 youngest consolidated rocks in the region. The different 

 divisions, in a general way, are displayed over long areas 

 trending east and west, parallel to the coast line — the 

 highest divisions bordering the coast, the lower divisions 

 developed inland towards the south and resting on Cam- 

 brian and Pre-Cambrian strata. The Pre-Cambrian com- 

 prises plutonic, volcanic, and highly metamorphosed 

 sedimentary strata; the Cambrian is mainly of sediments 

 which are in part fossiliferous. 



The Carboniferous area, bordered on the north and east 

 by the Atlantic, is essentially a low, rolling country seldom 

 rising higher than 350 feet (105 m.) above the sea while the 

 Pre-Cambrian and Cambrian areas situated to the south 

 and west are more broken and in part consist of long 

 ranges of high hills rising abruptly from partly encircling 

 Carboniferous lowlands, to heights of from 500 to 1,000 feet 

 (150 to 300 m.) above sea level. The coast line is broken 

 by bays and channels of the sea running inland in a south- 

 westerly direction. One of the larger of these indentations 

 is that of Sydney harbour situated towards the centre of 

 the basin and forking towards its head into two arms each 

 of which is continued inland by a long valley. Farther 

 west, cutting through the Carboniferous lowland, are two 

 long channels leading southwestward into the salt water 

 Bras d'Or Lake which occupies so much of the central part 

 of Cape Breton island. 



The general southwesterly trend of the depressions 

 occupied by the sea, of the courses of the axes of folds 

 in the Carboniferous, and of the high ranges of Pre-Cam- 

 brian and Cambrian strata, is a marked feature. The 

 presence of the Carboniferous over the lowlands that 

 border and penetrate the high hills of Pre-Cambrian and 

 Cambrian rocks, the overlapping of various divisions of the 

 Carboniferous on these ancient strata, the relatively 

 undisturbed attitude and the comparatively coarse nature 

 of the bulk of the thick series of Carboniferous measures 



