SPAU CAVK. 



other respects it is calculated to excite. At the termi- 

 nation of the stalactitical ornaments there is a dark descent 

 for a few k yards, filled with rubbish from the ruins of the 

 roof above, which being here naked as well as accessible, 

 is plainly seen to be one of the trap veins. This vein 

 is here about ten feet wide, which is the general breadth 

 of the cave itself, and it is easy to see how by the wearing 

 out of its substance the excavation has . been formed, 

 having subsequently acquired its present degree of orna- 

 ment by the infiltration of carbonate of lime. Considering 

 the great depth of this cave and its present distance 

 from the sea, we are inclined to inquire by what means 

 so extensive an excavation could have been formed, 

 and how the rock which has fallen from it has been 

 removed.. It is probable that the depth of water at 

 the face of the cliffs was once such as to permit the 

 ready access of the sea to them, and that at this period 

 the excavations so numerous on this shore were pro- 

 duced. The subsequent accumulation of rubbish formed 

 by its action, has in later times produced the slope or 

 shore which now excludes it from further access and 

 protects the cliffs from further demolition. 



In the excavations which are found in the floor 

 of this cave we have the means of seeing the process 

 by which calcareous spar is formed, the crystallization 

 being carried on in a solution of the carbonate of lime, 

 precisely as it is in the saline solutions in our laboratories. 

 All these small pools are filled with groups of crystals, 

 in a state of constant augmentation, and all of them, 

 however accumulated, displaying the primitive rhomb. 

 Doubtless, these forms must be affected by the agitation 

 which the falling drops occasion in the solution; and it 

 is in all probability owing to some circumstances of this 

 nature, constant in the same spot but varying in different 

 situations, that crystals of one form are found to affect certain 

 places, while in others they regularly assume some other 



VOL. i. T 



