712 Miniature Physical Geology . [December, 
stone above, being no longer supported, break off and dash 
to the base of the Falls. It is partly owing to the faCt that 
the shale is undermined in this way that it is possible to 
walk for some distance under the Falls. When I was at 
Niagara it was not possible to go very far, but the scene was 
sufficiently striking. It was winter, and all the edge of the 
waterfall was fast locked in the icy grip of frost. On looking 
up, therefore, I saw hanging above me festoons of icicles, 
some of them a hundred feet long. With difficulty — for the 
rock was glazed with ice — I proceeded still under the Falls, 
and then, on looking up, I saw that which I shall never for- 
get : the whole river took its mighty leap, and fell with a 
bewildering roar at my very feet. Though almost blinded 
by the spray, which froze to my hair and beard, I could not 
take my eyes from the curving green mass of water which 
shot over my head. In ten minutes I learnt a lesson con- 
cerning the power of water that the reading of a lifetime 
would not have taught me. 
Of this cutting backwards, which in the case of Niagara 
is at the average rate of nearly a yard per annum, it is not 
difficult to find miniature examples. In a note-book, for 
instance, I find the following : — “ Near Reculver, in Kent, a 
small stream is led through pipes from the Coast-guard Sta- 
tion to the cliff. This stream has formed a little valley by 
cutting backwards. Between a ploughed field and the edge 
of a cliff there is a band of about 2 yards of grass. The 
little valley formed by this stream has cut its way backwards 
through the grass, and for a distance of some 6 or 8 yards 
into the ploughed field. The whole has evidently been 
effected so recently that it forms an instructive example of 
geological aCtion on a small scale.” Below the waterfall, 
again, at Black Gang Chine, Isle of Wight, the little stream 
falling from a thick ledge of hard sandstone, over softer, 
more friable sandstone, affords a good small scale illustration 
of the aCtion of the water at Niagara. On the way up 
Table Mountain, once more, above Bishop’s Court, when the 
first ridge or terrace is reached, the path passes a miniature 
example of similar aCtion, the place of the upper ledge of 
limestone being in this case taken by matted grass. 
IX. The Formation of Deltas. 
On the Ramsgate sands many of the miniature rivers flow 
into pools which are miniature seas or lakes. “ I have often 
seen one of the streams in the course of an hour fill up a 
considerable bay, and push its delta far out to sea. The 
