250 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



In the Eastern Province the deposits of Pennsylvanian time below the 

 middle Conemaugh are limestones, gray and black shales, and light-colored 

 sandstones, evidently deposited in swamps or shallow basins subject to 

 invasions by marine waters. The deposits were derived from low lands at 

 great distances and laid down in either a submerged area or areas in which 

 the water-table reached the surface, so that the iron which furnished a large 

 part of the coloring matter remained in the ferrous condition. 



The elevation of the eastern side of the continent was apparently beyond 

 the limits, to the east, of the Appalachian trough, as is evidenced in the 

 accumulation of conglomerates to the north and west of the Cobequid 

 Highlands of Canada and in the Boston Basin. In the latter region the 

 elevation was sufficient to produce at least local glaciation. To the south 

 the elevation was less, but still sufficient to expose the igneous rocks of the 

 pre-Cambrian core of Appalachia to the vicissitudes of a rigorous climate 

 with wet and dry seasons. It is not necessary to assume that the climate 

 was glacial or even semiglacial in the latitude of Pennsylvania and West 

 Virginia; it may have been not unlike that of the present day, for red 

 deposits are forming now in the Potomac River and the conditions in the 

 southern Appalachians and upon the Piedmont Plateau are just such as 

 would permit the formation of red sediments. Such an assumption is not 

 inconsistent with the conception of local glaciation on higher areas, as, for 

 instance, southeast of the Boston Basin. 



The sudden change in the sediments and the uplift which they reveal, 

 with the consequent climatic changes, are decidedly inconsistent with current 

 conceptions of uniform conditions prevailing throughout Pennsylvanian time. 

 The picture drawn by David White (see page 233) and the idea of a uniform 

 climate prevailing over the earth from pole to pole^ is as correct as may 

 now be given for the preserved portion of the Pennsylvanian series in the 

 western part of the Eastern Province, but is applicable in the eastern part 

 of the province to only those portions which lie below the red beds (middle 

 Conemaugh). 



As bearing upon this point it is of value to quote from a paper by 

 Matthew, whose expressions are those of a trained vertebrate paleontologist. 

 In remarking upon Chamberlin's theories of climatic changes, he says:^ 



" Chamberlin's theories are to-day well known and are year by year gaining 

 a wider acceptance. So far as they pertain to the present subject, they differ 

 from the older prevailing concept of geological climatic conditions chiefly in that 

 they involve an alternation of climates through the course of geologic time from 

 extremes of warm, moist tropical and uniform, to extremes of cold, arid zonal 

 climates. The former are the results of prolonged base-level erosion and the 



^ White, David, and F. H. Knowlton, Evidences of Paleobotany as to Geological Climate, 



Science, vol. 31, p. 760, 1910. 

 * Matthew, W. D., Climate and Evolution, Annals New York Academy of Science, vol. 



XXIV, p. 173, 1915. 



