FORMATION OF CLIFFS WITH PLATFOEMS. 



155 



tation begins to show itself on the cliffs at the border of the Mediter- 

 ranean.* 



Notwithstanding the astonishing variety of aspect presented by 

 cliffs composed of various substances, chalk, marble, granite, or por- 

 phyry, we can still observe one trait of singular resemblance in 

 the form of the rocks, which are covered by the waters of the sea 

 at the foot of the abrupt walls. This feature consists in the exist- 

 ence of one or two platforms of varying dimensions, situated at the 

 base of the escarpments. On the coasts of the Mediterranean and 

 other seas with a very slight tide, where the level of the waters 

 hardly varies excepting under the influence of the winds and storms, 



Fig. 61.— Cliff on the Mediterranean. 



there is but a single one of these platforms, while on the shores of 

 the ocean, where the tides attain a height of at least several yards, 

 two steps, one above the other, extend below the wall of the cliffs. 

 When the rock is very hard the platforms present but a few yards 



i 



Fig. 62.— Ocean Cliff. 



Boblaye et Virlet. G. Collegno ; Gcologia delV Italia. 



