of the Bahama Islands. 315 



sands, it may be surmised that the Bahama Delta has had the advantage of 

 such ready-made base and submarine nucleus of aggregation." 



With respect to the present surface condition of the 

 Bahamas, as compared with that of the Bermudas, the evi- 

 dence lately made known by Mr. J. Matthew Jones of sub- 

 sidence in the latter should not pass unnoticed. 



In a communication published in "Nature" (Aug. 1, 1872), 

 Mr. Jones explains that about two years ago submarine blast- 

 ings were carried on at the entrance of Hamilton harbor, and 

 at a depth of over six fathoms a cavern was broken into 

 which contained stalactites and red earth. Also, that durino- 

 the past two years similar blasthigs had taken place inside an 

 artificial harbor, situate at the western extremity of the 

 islands, for the purpose of forming a bed of sufficient depth 

 for the reception of the great dock constructed several years 

 ago, in England. 



Mr. Jones thus states and comments on the results : — 



" The excavations extended to a depth of 52 feet below low water mark. 

 At 46 feet occurred a layer of red earth 2 feet in thickness, containing 

 remains of cedar trees, which layer rested upon a bed of compact calca- 

 reous sandstone. Here we have the first satisfactory evidence of the 

 submergence of an extensive deposit of soil once upon the surface, and 

 that to the depth of 48 feet below the present low water level, which con- 

 sequently grants an equal elevation above it in former times. Now on 

 carefully surveying the Bermuda chart, we find that an elevation of 48 

 feet will bring the whole space which intervenes between the present 

 land and the barrier reef, now covered with water, above the water level. 

 This attained, what more is required to prove the former extent of the 

 island group, before the present submergence, to the present barrier 

 reef? 



Mr. Jones promises further evidence on this interesting 

 subject. 



Whether any similar proofs of subsidence have been 

 noticed in the Bahamas, I am unable to state. 



I now propose to consider the evidence afforded by the 

 distribution of the Land Shells on the Bahama Islands. 



