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-Cornwallis Valley, 
are wide enough to permit of the entry of efficient tidal currents to any 
considerable distance from the gates, even undér 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 
