THE TWO GREAT SCULPTORS. 
117 
the cliff is undermined and large pieces fall down. 
These pieces are in their turn ground down to pebbles 
which serve to batter against the remaining rock. 
Professor Geikie tells us that the waves beat in a 
storm against the Bell Rock Lighthouse with as much 
force as if you dashed a weight of 3 tons against 
every square inch of the rock, and Stevenson found 
stones of 2 tons' weight which had been thrown during 
storms right over the ledge of the lighthouse. Think 
what force there must be in waves which can lift up 
such a rock and throw it, and such force as this beats 
upon our sea-coasts and eats away the land. 
Fig. 28. 
Cliffs off Arbroath, showing the waste of the shore. 
Fig. 28 is a sketch on the shores of Arbroath which 
I made some years ago. You will not find it diffi- 
