52 DIVERSIONS OF A NATURALIST 



waves. Such a raised beach is seen along the rocks 

 bordering Plymouth Sound, at a height of some I 5 feet 

 (so far as I can, at this moment, remember) above high- 

 water mark. Owing to the fact that the rock is lime- 

 stone, and is dissolved and redeposited by rain water, as 

 a rock of sugar might be, the pebbles and shells of the 

 old beach are all stuck together or " petrified " by re- 

 deposited limestone (carbonate of lime). Lumps of it 

 can be carried away as specimens. 



Geological deposits of much older date than these 

 comparatively recent raised beaches tell us of the rising 

 of great masses of land. Thus, for instance, marine 

 shells in a deposit not quite so old as our chalk cliffs 

 and downs, are present at a height of 1 0,000 feet, forming 

 part of the Alps. At one time that very spot was the 

 bottom of the ocean, whilst other tracts of the earth's 

 surface, now sunk hundreds of fathoms below the sea- 

 level, stood out as continents, with hills and valleys well 

 raised above the waters. Direct evidence of the recent 

 sinking of the coast as distinct from its erosion is not 

 familiar to us in England. The evidence of it is 

 naturally obliterated, as the sinking goes on, whereas on 

 a rising coast the evidence is as naturally preserved. 

 But on the shores of the Mediterranean near Naples the 

 evidence of sinking is well preserved, and has been 

 carefully studied and recorded. The ancient Roman 

 road is still sunk beneath the water, though the celebrated 

 temple of Puteoli, which was formerly submerged by the 

 sinking of the land, has reappeared by a subsequent 

 elevation of the same area. This has not brought the 

 site to so high a level as it had when the temple was 

 built, as appears from the fact that the Roman paved 

 roadway close by is still some I 5 feet below the surface 

 of the sea. 



