368 THE CANADIAN NATURALIST. [Vol. 



IX. 



TIDAL EROSION IN THE BAY OF FUNDY. 



By G. F. Matthew. M.A., F.G.S. 



The causes which produced the pheuomena of the Post-pliocene 

 period in the northern parts of Europe and America have been 

 the subject of controversy for many years ; and even now, so far 

 as some of them are concerned, are open to debate. Among the 

 deposits whose origin seems obscure, may be classed the isolated 

 ponds, gravel mounds, and "moraine ridges" met with in 

 STavelly tracts in Canada and New England. By some geologists 

 these deposits are attributed to the sudden melting of glaciers of 

 great extent which once covered the northern parts of the conti- 

 nent; by others to heavy spring-floods from snow-clad regions, 

 and by a third class to strong marine currents. Where such 

 deposits are found in the neighborhood of mountains it may be 

 supposed that one or other of the first two causes has produced 

 the beds. But the absence of mountain chains from all parts of 

 the Maritime provinces of Canada except the north, is an objec- 

 tion to the use of these hypotheses in explanation of the condi- 

 tions of the deposits which exist there. Supposing from the 

 condition of the gravel and sand beds spread over parts of 

 southern New Brunswick that such accumulations may have 

 been due to ocean currents, I was led to examine the efi'ects of 

 tidal currents in the Bay of Fundy in removing and rearranging 

 the sediments on its bottom. The action of the tides in these 

 respects was found to present phenomena analogous to those 

 which ocean currents would have produced ; though of course 

 not identical with them, or on so large a scale. 



The following results of observations on tidal erosion are based 

 chiefly on an examination of the soundings in various parts of 

 the Bay of Fundy obtained by the British Admiralty Survey, 

 with supplementary data embodied in the map obtained from an 

 article in the report of the Smithsonian Institution of 1874 by 

 Prof. J. E. Hilgard, and results of the deep sea explorations of 

 the Challenger expedition on this coast. 



Investigations into the condition of the sea-bottom made in 

 recent years, show that except where it is swept by currents, the 

 ocean-floor is covered by a fine mud or even a flocculent ooze ; 

 while on the shallows along the coast are strewn the sand, gravel 



