110 TRANSACTIONS OF THE [jAN. 18, 



of from three to four feet. At low tide, water passes through 

 numerous openings from the sound to the harbor. 



The caverns between the sound and the harbor have been de- 

 scribed by many visitors to the islands. Joyce, the Walslnghara 

 group, Paynter's Yale, Shark's Hole and several others of great 

 beauty and much interest are in the limestone. Tucker's island 

 off Somerset, has a similar cave in the same rock. All of these 

 great caves show massive columns, occasionally several feet in 

 diameter and very many of them parti}' or wholly below water 

 level. Even the higher places are honeycombed, for caverns 

 were seen beginning in the softer rock at seventy feet above tide 

 and descending rapidly to the water. But the great caverns are 

 in the limestone, which is tenacious enough to be a good roof; 

 caves in the sandstone are not, cannot be extensive, as the roof 

 falls too readily and a sink is formed. A sandstone cave on Mr. 

 W. S. Peniston's property near Harrington sound shows this con- 

 dition well ; it has no stalactites. 



Sir Wyville Thomson* thinks the caves due to the action of 

 running water as a mechanical agent in removing the softer part 

 of the limestone and thereby making channels for itself. This 

 is unquestionably true for the sandstone, but it can hardly be 

 equally so for the limestone, as that rock rarely shows any soft 

 or incoherent layers. The limestone is alwaj'S cemented, the 

 sandstone rarely so. 



Collapsing roofs of caverns are by no means unusual phenom- 

 ena in the Bermudas. Only a few years ago an enormous mass 

 fell from the Abbot's cliffs near Harrington sound and less im- 

 posing falls occur frequentl}' around that sound. The roofs of 

 many of the caverns are in dangerous condition and in some 

 cases great falls took place so recentl}' that new stalactites have 

 not been formed, though the dripping is constant. Tiie move- 

 ment of the roof is proved distinctly in several caverns ; great 

 columns in Tucker's Island cave are fractured across the top 

 and bottom, the fracture being so recent that the crevices are 

 still open, though the formation of stalagmite is still going on. 

 A similar condition was observed in one of the caverns between 

 Harrington sound and Castle harbor. The ragged borders of 

 the cave entrances tell the same story, for most of them are 

 reached through a basin with abrupt sides and sometimes of 

 considerable extent. 



The Submerged Area. 



Sailing upon the lagoon or other bodies of water within the 

 P>ermudas, one notices especiall}' the " flats," level surfaces but 



* The Atlantic, Vol. I., p. 293. 



