412 A. Agassis — Notes from the Bermudas. 



also underlie the so-called patches and heads forming the flats 

 which extend on both sides of the main channel and divide the 

 interior waters of the Bank into irregular sounds like Murray 

 anchorage. The passage of the shore aeolian rock ledges into the 

 coral patches can easily be traced both off the north and south 

 shores. 



I fully agree with those who before me have examined the 

 Bermudas and who consider that subsidence has brought about 

 the existing outlines of the islands. But that is a very differ- 

 ent thing from assigning to the corals now growing the forma- 

 tion of the islands owing to this subsidence. That the proto- 

 bermudian land was of elliptical shape and owed its existence to 

 the action of winds sweeping over an extensive coral beach 

 from which was gathered the materials which now form the 

 solidified aeolian hills of Bermudas no one can question. But 

 there is no evidence to show that the original annular coral reef 

 was formed during subsidence. That reef has disappeared and 

 nothing is left of it except the remnants of the asolian ledges 

 extending to 16 or IT fathoms outside of the reef ledge fiats, 

 ledges which owed their existence to the material derived from 

 it : the former seolian hills of the protobermudian land. 

 Remnants of such ledges and former aeolian hills are the rocks 

 forming the outer ledge flats, the breakers all along the south 

 shore, the Mills breaker, the North Rocks, the Chub-heads, 

 the South-west breaker and others. 



The Bermudas and Bahamas offer an example of the 

 thickness of a recent limestone deposit during a period of 

 rest. Assuming a probable subsidence of 70 feet and a 

 greatest elevation of 260 feet we get a coral limestone of 330 

 feet in thickness, the material of which has all come from a reef 

 which itself was probably not thicker than 120 feet or a total 

 thickness of 450 feet. In the case of the Bahamas the maxi- 

 mum height of the seolian hills is stated to be about 100 feet 

 and the greatest subsidence was probably as much as 200 feet 

 which with the thickness of the reef would give a thickness of 

 720 feet of coral limestone. This thickness or a great part of 

 it moreover is not limited to a circumscribed area but extends, 

 as is the case of the Bahamas, over a wide region. When we 

 remember how readily these coral limestones are changed into 

 hard ringing rocks we introduce a new element into the dis- 

 cussion of the mode of formation of huge masses of limestone 

 especially in the region of the trade winds. 



Solution has undoubtedly played some part in producing the 

 fantastic outlines of the limestone ledges as well as of the shore 

 rocks below low-water mark but the solvent action of the salt 

 water cannot be compared in efficiency to the destructive 

 mechanical action of the sea. This has to a great extent been 



