THE PIGEONS' CAVE. 377 



effect on a drill of turnips. Beneath the guano we 

 found a loose gravel, which became less loose as we 

 went down, and then passed into a sort of breccia bound 

 together by a brown oxide of iron. We found neither 

 shells nor bones. We then opened another pit about 

 fifty feet further in, the guano was wanting, but the 

 gravel bore the same appearance as in the other open- 

 ing. There are masses of gravel that project, strongly 

 enough, from the sides of the cave at the height of four 

 and five feet from the floor. Some of them stick out 

 like fragments of cornices for fully two feet, bound 

 together by stalactites. They show that the bottom of 

 the cave must have at one time stood that high, that the 

 stalagmitical matter running from the sides bound into 

 coherent masses the stones and gravel in contact with 

 them, and that the sea then swept the loose matter away, 

 leaving the projections to be crusted over still further by 

 the stony cement. We broke into several of the bulkier 

 of them and found them composed of water-rolled peb- 

 bles and very distinct fragments of shells. I procured 

 a specimen in which there are five well-marked bits of 

 shell rounded on the edges as we find such fragments 

 on surf-beaten and rocky shores. How strange a re- 

 cord ! We have evidence all around the coast in our 

 raised beaches that the sea once stood higher on the 

 land than it does now ; but we see here that there must 

 have been an alternation of elevations and depressions. 

 When these shells were rolled in on the floor of the 

 cave, a floor standing five feet above its present level, 

 the sea must have stood high. During the time when 

 they were consolidating through the agency of the 

 stalagmitical matter, the sea must have fallen, otherwise 

 the consolidation could not have taken place. It must 

 then have again returned and washed out the loose 



