68 THE SHORE 



horizontal terraces above the shore should be at once 

 investigated. When examined, they are found either to 

 be shelves, cut out of the rock below by wave action, 

 often strewn with pebbles and marine remains ; or to 

 be artificial formations of limestone, implanted on the 

 rocky slope below for a foundation. If, as on many 

 islands, there are series of these terraces, specimens of 

 the rocks of each should be carefully collected at 

 different elevations ; their heights above sea-level 

 should be ascertained (a good pocket aneroid with 

 scale of heights is useful) ; and their surface, appear- 

 ance, and extent should be noted down, especially the 

 existence or non-existence of caves. Often the slopes 

 of the land are so steep and the rainfall is so abundant 

 that only traces of elevated rocks are found at the sides 

 of the valleys, and sometimes even these are lost. Yet 

 evidence of elevation may be found in the existence 

 of isolated caves and overhanging rocks, or even scat- 

 tered marine shells. 



All the above land formations, wherever found, should 

 be compared with the present action of the sea on the 

 same coasts. This latter has its own importance as 

 well, and should be studied all round the land to 

 windward and to leeward, where the current directly 

 strikes on the land to pass out in an undercurrent 

 which curls round its points, where it merely sweeps 

 the capes as it passes by, and where it curls round them 

 forming eddies. The action of the sea on the rocks 

 of the shore is important, and the rocks themselves 

 should be examined, to see how far they are protected 

 by corals, Lithothamnia (massive red and white en- 

 crusting calcareous plants), seaweeds, barnacles, and 

 other organisms. Masses of rock, small islets near the 

 main mass of land, require examination in order to see 

 to what causes they owe their present isolation. The 



