DALY: PHYSIOGRAPHY OF ACADIA. 91 



"antecedent" tidal run-way or sound of great dimensions. Or it might 

 be that the tilting of the peneplain was so rapid as nearly to obliterate 

 the Bay of Fundy of that time. Could the weak tidal currents then 

 deepen and lengthen the remnant of the bay as well as remove the large 

 amount of land-waste brought to the shore by the revived streams '] 

 Again, would the minor oscillations of level expected during the long 

 period following the last great uplift, occasion repeated drowning of the 

 river-valleys and therewith increased excavating power of the currents, a 

 power perhaps comparable to that of the present Fundy tides ? Similar 

 questions would arise in the discussion of the ideal " tide-cycle," which is 

 yet to be invented. Where so little has been done towards discovering 

 the criteria for a tidal plain of denudation as distinguished, from a pene- 

 plain or from platform of wave-erosion, it does not seem possible to get 

 very far in finding a complete history of the Bay of Fundy. There are 

 too many unknown elements in the problem to permit of its complete 

 solution. We are sure that tidal work cannot be ruled out ; we know 

 as well that certain facts lead to the conclusion that a part, perhaps the 

 major part, of the excavation has been done by subaerial processes. 



Some of these facts have been already noted. In addition, it may be 

 questioned that the gates opening into the Annapolis-Corn wallis Valley, 

 are wide enough to permit of the entry of efficient tidal currents to any 

 considerable distance from the gates, even under the present conditions 

 of extraordinary tidal ranges. These openings are wider now than they 

 have ever been before ; yet scouring action is confined to the vicinity of 

 St. Mary's Bay, Digby Gut, and Minas Channel, and elsewhere deposi- 

 tion is taking place. Secondly, the development of the Trias at the 

 sea-wall, at Bridgetown, at Middleton, and at other points in the valley 

 seems to show a greater sympathy of the pre-glacial bed-rock topography 

 with pre-glacial St. Mary's, Annapolis, and Cornwallis rivers rather than 

 with the graded slopes towards St. Mary's Bay and Minas Channel ex- 

 pected if the tides did the excavation. At least one other large feature 

 of the unsubmerged Triassic suggests river-work, and it is fair to lay 

 emphasis on even a single instance of the kind where so much of the 

 physiographic record is drowned beneath the waters of the bay. I refer 

 to the long trench which has been hewn out of the amygdaloid lying 

 between the two trap ridges of Digby Neck. Here, as in the case of 

 the Annapolis Valley, tidal erosion would be very unlikely to produce a 

 submarine valley of such length and narrowness. The six-knot flood and 

 ebb past the southwest ends of Long and Briar Islands does not seem to 

 be appreciably lengthening, by differential erosion, the small inlets located 



