H6 THE FAIRY-LAND OF SCIENCE. 
the rock, and grinding the pebbles which it has 
brought down, against the bottom and sides of this 
hollow, just as you grind round a pestle in a mortar. 
By degrees the hole grows deeper and deeper, and 
though the first pebbles are probably ground down 
to powder, others fall in, and so in time there is a 
great hole perforated right through, helping to make 
the rock break and fall away. 
In this and other ways the water works its way 
back in a surprising manner. The Isle of Wight gives 
us some good instances of this; Alum Bay Chine and 
the celebrated Blackgang Chine have been entirely 
cut out by waterfalls. 
But any ravines cut by water in England are as 
nothing compared with the canons of Colorado. Ca- 
non, is a Spanish word for a rocky gorge, and these 
gorges are indeed so grand, that if we had not seen in 
other places what water can do, we should never have 
been able to believe that it could have cut out these gi- 
gantic chasms. For more than three hundred miles the 
River Colorado, coming down from the Rocky Moun- 
tains, has eaten its way through a country made of 
granite and hard beds of limestone and sandstone, and 
it has cut down straight through these rocks, leaving 
walls from half-a-mile to a mile high, standing straight 
up from it. The cliffs of the Great Canon, as it is 
called, stretch up for more than a mile above the river 
which flows in the gorge below! Fancy yourselves 
for a moment in a boat on this river, as shown in 
Fig. 29, and looking up at these gigantic walls of 
rock towering above you. Even halfway up them, 
a man, if he could get there, would be so small you 
