106 THE WORLD'S LUMBER ROOM. 



gain the best idea of what Nature's wear and tear really 

 means. For " the entire mass of stratified deposits is the 

 measure of former denudation." In England, roughly 

 speaking, all the rocks, with the exception of the granite 

 hills of Cornwall, Devon, and Worcestershire, are stratified, 

 i.e., have been deposited in beds or strata at the bottom of 

 seas or lakes, or at the mouths of rivers ; all have had a 

 previous existence in some other shape, and have been worn 

 away from some unknown land, which we may dream of as 

 Atlantis if we will. 



Rivers are the great carriers, and if the refuse conveyed 

 by them has had a long journey, the visible part of it 

 reaches the sea in the form chiefly of mud and sand,* which 

 are both usually deposited within one or two hundred miles 

 from the shore, though the finest portion may be carried 

 farther, especially where the current is strong, and if it 

 becomes entangled in ice, is, of course, carried much farther 

 still. 



Much of the sand remains close in shore, forming shoals 

 and sand-banks, and much is thrown up on the beach, where 

 it is dried by the wind, and then, unless there are cliffs or 

 rising ground to stop it, is frequently blown inland again, 

 and piled up into sand-hills, which drift farther and farther 

 year by year, swallowing up houses, villages, and even forests. 



This is what the sand has done on the flat coasts of 

 Jutland, and the Bay of Biscay. The Landes, as the sand- 

 dunes are called in France, extend from the Garonne to the 



* The beach pebbles are, for the most part, made by the action of the 

 waves on the coast, and though often swept along it, are seldom carried out 

 to sea. 



