THE MODERN I'ERIOD. 15 



ascertained by Billings in the rocks of Anticosti, and unique in 

 North America, furnishes an excellent illustration of this. In 

 the Carboniferous period the Gulf of fSt Lawrence was a sea 

 area as now, but with wider limits, and at that time its southern 

 part was much filled up with sandy and muddy detritus, and its margins 

 were invaded by beds and dykes of trappean rocks. In the Triassic 

 age the red sandstones of that period were extensively deposited in 

 the Acadian Bay, and in part have been raised out of the water in 

 Prince Edward Island, while the whole bay was .shallowed and 

 partially separated from the remainder of the gulf by the elevation 

 of ridges of Lower Carboniferous rocks across its mouth. In the Post- 

 l)liocene period, that which immediately precedes our own modern 

 age, as I have elsewhere shown,* there was great subsidence of this 

 region, accompanied by a cold climate, and boulders of Lanrcntian 

 rocks were drifted from Labrador and deposited on Prince Edward 

 Island and Nova Scotia, while the southern currents flowing up what 

 is now the Bay of Fundy, drifted stones from the hills of New 

 Brunswick to Prince Edward Island. At this time the Acadian 

 Bay enjoyed no exemption from the general cold, for at Campbell- 

 ton, in Prince Edward Island, and near Bathurst, in New Brunswick, 

 we find in the clays and gravels the northern shells generally charac- 

 teristic of the Post-pliocene, — though perhaps the lists given by Mr 

 Matthew for St John, and by Mr Paisley for the vicinity of Bathurst, 

 may be held to show some slight mitigation of the Arctic conditions as 

 compared with the typical deposits in the St Lawrence valley. Since 

 that time the land has gradually been raised out of the waters, and 

 with this elevation the southern or Acadian fauna has crept north- 

 ward and established itself around Prince Edward Island, as the 

 Acadian Bay attained its present form and conditions. But how 

 is it that this fauna is now isolated, and that intervening colder waters 

 separate it from that of Southern New England? Verrill regards this 

 colony of the Acadian Bay as indicating a warmer climate intervening 

 between the cold Post-pliocene period and the present, and he seems 

 to think that this may either have been coincident with a lower 

 level of the land sufUcient to establish a shallow-water channel con- 

 necting the Bay of Fundy with the Cinlf, or with a higher level raising 

 many of the banks on the coast of Nova Scotia out of water. Geo- 

 logical facts, which I have illustrated in Acadian Geology, indicate 

 the latter as the probable cause. We know that the eastern coast 

 of America has in modern times been gradually subsiding. Further, 

 the remarkable submarine forests in the Bay of I^undy show that 



* Notes on rost-plioccne of Canada, Canadian Naturalist, ls7'2. 



