a i 
ad Geology and Topngraphy of Wester New York: 99 
a quence of the contraction-of | “the channel. This wave terminates 
abruptly on the inland side, because the quantity of water con- 
tained in it is so great, and its motion so rapid, that time hed 
allowed for the surface of the river to be immediately raise 2 
means of transmitted pressure. A tide-wave thus rendered a s: 
rupt, has a close analogy, observes Mr. Whewell, to the waves _ 
which curl over and break on a shelving shore.” ‘This phenom- 
enon takes place in the river Severn, which enters the Bristol 
channel, where the Bore, during spring tide, is sometimes nine 
feet high, and rushes up the channel with extraordinary rapidity.* 
It also occurs in the Ganges, the Burrampoote id the Hoogly 
rivers ; sweeping off herds of cattle, or what - else may be 
caextabaint in its course, and occasions more or less i ciiiaaal to 
the safe navigation of all these streams. 
At any rate, the tide in the vicinity of the Niagara must hace 
been very considerable ;, and its power, combined with the dash- 
ing of the waves, seems to be the only rational cause which can 
x be assigned for the excavation of the numerous ravines already 
noticed.. In a paper by Mr. James Geddes, read before the Al- 
bany Institute,{ the fact, that they owe their: origin to other than 
existing causes; is Slnealet established. 
' When. the elevation had so far advanced a as to ahen the. 
current exclusively to the valley of the Niagara, and the chan- 
nel below the present falls sufficiently deepened to receive and 
confine the tidal wave within its rocky walls, a power was 
brought into active operation which it is difficult fully to con- 
ceive without witnessing its effects on some of the iron-bound. 
coasts of this continent. The basin of Mines, and its. vicinity, 
at the head of the Bay of Fundy, would probably be a fit Bere 
- to study the effect of causes which were once active here.:. 
When we contemplate these powerful agents, which, in every 
country, have had so much to do in shaping. the surface of the 
earth, and consider, that in the natural order of events they must 
have been active here; when we find the proofs of their visitan, 
tion. engraven in shaescian as enduring as the continent itself, 
we ean hardly doubt that they played an important part.in exca- — 
vating abe deep channel below. the falls. And when we contem- 
a 
" * Lyell’s cee Vol. 1, p. 274. 
t Rennell, see Philosophical ‘Transactions of the Royal Society, 178I. 
¢ See American ere Vol. 11, p. 213. 
