56 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



aceous elements were removed through oxidation under subaerial conditions. 

 There was at this time a return to more arid conditions very similar to those of 

 the millstone grit." 



In a later paper Bell says : J 



"The overlying Boss Point rocks are characterized by grey sandstones bearing 

 abundant drift plant debris, which are like those of the higher beds, i. e., of 

 Pennsylvanian age, and by the occurrence of basal conglomerates and channels 

 or lenticular beds of the peculiar limestone conglomerates, referred to above. 

 These latter, in addition to the nodules of unfossiliferous limestone, contain 

 pebbles of red sandstone and shale, all of which could have been derived from 

 the underlying rocks of Windsor age, such as are still seen at Dorchester. ..." 



The Boss Point formation, which is, roughly at least, regarded as 

 equivalent to the Pottsville, is stated to be 



"Made up of two quite distinct divisions, a lower predominantly red division 

 and an upper prevailingly grey division. The lower red division consists of 

 varying proportions of brick-red quartz conglomerates and red argillaceous sand- 

 stones and shales. The upper division is made up chiefly of greenish grey, 

 yellow-weathering sandstone, interbedded with brick-red argillaceous shales, and 

 with subordinate grey shales as well as thin seams of coal or carbonaceous shales, 

 and thin beds of bituminous fossiliferous limestone. The typical sharp quartz 

 sandstone of the upper division occurs at Boss Point, which name is accordingly 

 chosen to designate the formation. In the Joggins section the conglomerates, 

 aside from the limestone conglomerates already mentioned, are confined to basal 

 members, but in New Brunswick they are much more prevalent." 



According to this author, the Cobequid Mountains were subject to 

 periodic uplifts in pre-Mississippian times and existed during the Missis- 

 sippian as highlands or islands in the sea, being subject at this time to active 

 erosion. At the close of Mississippian there were, apparently, warping 

 movements parallel to the Appalachian axis somewhere south of the Cobe- 

 quids which probably affected the height of this land and furnished the 

 material for the Boss Point and Joggins formations. 



Bell suggests that the change in sediments was in part due to a climatic 

 change with increased humidity and more fluviatile conditions, with the 

 accumulation of flood-plain and delta deposits. 



The Joggins formation is separated from the Boss Point, according to 

 Bell, by 'a disconformity. The red shale and sandstone (2,000 feet) earlier 

 placed at the top of what is now called the Boss Point, is represented in the 

 south limit of the anticline by 800 feet of coarse red conglomerate formed by 

 material derived from the underlying Cobequid group, the red shales of the 

 north limit being considered as an extension of this erosional and deposi- 

 tional interval. The various movements are discussed by Bell at some 

 length in the publication cited, pages 367 and 368. 



1 Bell, W. G., Summary Report of the Geological Survey Branch of the Department of 

 Mines for 1912, Ottawa, p. 366, 1914. 



