BERMUDA BIOLOGICAL STATION. 



405 



chief constituents being fragments of shells, serpula tubes and corallines. 

 There are no such stratified subaqueous rocks as are found in this 

 country, but everywhere the cut edges of the rocks show the peculiar 

 sinuous lines that characterize the stratification of drifting sands. 

 Most — if not all — of the harder rocks are doubtless the result of the 

 action of water and air on these aeolian masses. At almost every point 

 where the action of the sea is traceable it has resulted either in cement- 

 ing together the layers of these rocks till all evidence of stratification is 



Fig. 8. Water-worn Rocks, South Shore. 



lost, or else its mechanical effect has been more immediate than its 

 chemical, and the rock has crumbled into its constituent grains and has 

 become once more a sandy beach, in turn yielding up its substance to 

 build the present sand dunes of the coast, which have the same seolian 

 structure as their predecessors. 



The mechanical action of the sea operating on the already hardened 

 rocks has left them carved in the most fantastic shape (Figs. 8, 9), and 

 with edges so sharp that it is almost impossible to walk upon them. In 

 many places the rocks are honeycombed through the action of water, and 

 subterranean passages connect inland waters with the sea. Caves, too, 

 sometimes of considerable extent, are found at various places, especially 



