PHYSIOGRAPHY OF THE SEA-SHORE 35 



greater the resistance offered ; if the coast-line consists of 

 rocks of diiferent texture, the soft beds are worn into bays, 

 etc., and the harder beds stand out as promontories. Eroded 

 material may be removed below low-water mark, or drifted 

 laterally by currents and piled up elsewhere, with the result 

 that the land loses at some points, but gains at others, while 

 shingle banks, spits, and sand banks and bars are also 

 formed. It has been estimated that between the years 1863 

 and 1896, 35,444 acres were added to, and 4692 acres lost 

 to the United Kingdom through erosion. Lake {op. cit.) 

 also makes an interesting comparison between the coasts 

 of the west of Scotland and that of Cardigan Bay, in 

 West Wales. " Wales, like Scotland, is an ancient rocky 

 highland partially submerged, but while the west of Scot- 

 land is deeply indented the shore of Cardigan Bay is com- 

 paratively smooth. In the west of Scotland the tide 

 approaches and recedes at right angles to the general trend 

 of the coast, and the ebbing tide helps to keep the firths and 

 lochs free from deposits. In Wales the tidal wave runs 

 along the coast and sweeps the loose material into the 

 sheltered inlets. It is because nearly all the inlets are filled 

 with deposit that the outline of Cardigan Bay is smooth." 

 Protection, with the eflFect of reducing scour to relatively 

 harmless proportions, is a most important factor. The 

 eifects of moving sand banks can be well studied in con- 

 nection with the fauna of estuaries, and those of shingle on 

 many rocky shores. A certain amount of water movement, 

 on the other hand, is needful to provide oxygen content for 

 life processes, while tidal sweep and local currents play a 

 considerable part in faunal distribution. 



Many attempts have been made to classify the Littoral 

 Area — of which the tidal zone forms the upper portion — 

 each largely influenced by the particular region investigated. 

 Davenport divides the shore at Cold Spring Harbour Sand 

 Spit into (i) The Submerged Zone : all that portion of the 

 beach below mean low tide, but which may be exposed by 

 the lowest spring tides ; a region usually covered with 

 water. (2) The Lower Beach : this lies between mean low 



