1865.] DAWSON COAL-FOEMATION. 99 



which the areas now under consideration were in the condition of 

 shallow seas or swampy flats, the greater part of the Lauren tian and 

 Silurian districts of North America existed as land ; while the great 

 number of Coal-formation plants common to Europe and America 

 may indicate the existence of intermediate lands now submerged. 

 From such lands, undergoing waste during the long Carboniferous 

 time, the materials of the shales and finer sandstones may have been 

 derived. 



Taking this view of the source of the sediment, we should infer 

 that the time of the formation of the marine limestones was that of 

 greatest depression of the land, when the local ridges of older rock 

 were mere reefs and islets, and when sediment from more distant 

 lands was deposited only at intervals. We should also infer that the 

 time of the formation of the coal-beds was that of greatest elevation, 

 when the former sea-bottoms had become land-surfaces or flats, 

 exposed only to occasional inundation, and when rivers were bearing 

 downward from large continental regions great quantities of fine 

 silt. Further, the conditions of the Millstone-grit and of the Newer 

 Coal-formation must have beeli of an intermediate character, re- 

 quiring wide sea-areas receiving great quantities of sediment, and 

 on this account, as well as because of their shallowness, unfavourable 

 to marine life, while the areas of vegetable growth were also of 

 limited extent. 



It would also follow that when the Lower Coal-measures and 

 conglomerates were formed, the land was slowly subsiding ; that in 

 the time of the marine limestones it attained to its greatest depres- 

 sion, and long remained nearly stationary ; that in the Millstone- 

 . grit period there was re-elevation, and that in the period of the 

 Middle Coal-formation and Newer Coal-formation there was again 

 subsidence, slow and interrupted at first, but subsequently of greater 

 amount. From the absence of Permian deposits it Liay be inferred 

 that elevation again took place at the close of the Carboniferous period, 

 to such an extent as to preclude further deposition in the area in 

 question ; while the red sandstone and trap of Mesozoic age indicate 

 the recurrence at that time of conditions somewhat similar to those 

 of the beginning of the Carboniferous period. 



The general phenomena of deposition above indicated apply to all 

 the Carboniferous areas of Nova Scotia and New Brunswick, and, so 

 far as known, to those of the Magdalen Islands and of Newfoundland. 

 But, as I have pointed out in * Acadian Geology,' numerous local 

 diversities occur, in consequence of the interference of the older 

 elevated ridges with the regularity of deposition. In some places the 

 entire Lower Carboniferous series seems to be represented by con- 

 glomerates and coarse sandstones. In others, the Lower Coal- 

 measures, or the Marine Limestones, or both, are extensively deve- 

 loped. These local diflerences are, on a small scale, of the same 

 character with those which occur on a large scale in the Northern 

 and Southern Appalachian districts andWestern districts of the United 

 States, and in the different coal-areas of Great Britain and Ireland, 

 as compared with each other and with the Carboniferous districts of 



