SAND AND PEBBLES OF THE SEASHORE 49 



On other parts of the coast the beach " travels," 

 being driven along the underlying solid shore by the 

 prevailing direction of the tidal currents and by the 

 waves. The sea- waves break close to the soft cliffs 

 of clay, sand, and sandstone. These are continually 

 crumbling away owing to the action of land water, 

 which soaks from the surface down to the layers of clay 

 and forms subterranean springs and streams. They 

 undermine the face of the cliff and cause the upper parts 

 to topple. When there is a big, broad, growing beach 

 in front of such a cliff, the breaking down or " toppling " 

 of its face only leads to the formation of a slope (at the 

 " angle of rest "), and things remain but little changed 

 for ages. But if the beach is not being piled up and 

 added to and growing out seawards year by year, and is, 

 on the contrary, a travelling beach, then the sea comes 

 close up to the cliff, and when masses of it topple on to 

 the beach the sea washes them away, and no " slope of 

 repose " is formed. The cliff keeps on toppling as it 

 is undermined by springs of land water. Its natural 

 buttress against further breakage — namely, its own 

 fallen material — instead of resting against it as a great 

 sloping, protective bank, is washed away by the sea as 

 fast as it falls, and is carried down the coast by the tidal 

 currents. This is the story of " coast erosion " about 

 which there has recently been a Government inquiry. 

 Where the combined action of prevailing winds and sea 

 ; currents is throwing up and adding to the beach there is 

 ;no coast erosion. The causes of the sea currents on our 

 coasts are not easy to determine, as they are connected 

 [iwith the general contour of the land and the currents in 

 ' large tracts of sea, such as the Channel and the North 

 Sea. Coast erosion is a serious thing. Large parts of 

 the coast of Suffolk and Norfolk are being thus washed 

 away. It can be prevented by " holding " the beach 

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