234 MR. JUKES-BROWXE AND PROF. HARRISON 



broad. Parts of this, and especially the south-east corner, " exhibit 

 proofs of irregularity in the process of upheaval in a series of well- 

 marked terraces," which he compares with the terraces of Barbados 

 as described by Schomburgk. 



This tract appears to have been formed as a barrier-reef in front 

 of the ancient coast, which is defined by a parallel tract of gravelly 

 country at the foot of the hill range and at a distance of about 20 

 miles from the modern coast-line. The coral ridge rises to at least 

 150 feet above the sea, and where narrowest is backed by an equal 

 width of broad low-lying savannas ; but at the S.E. end it rises in a 

 series of terraces to the tlanks of the hills. 



Prof. Gabb describes its lithological characters as follows : — 

 '• The rock is evidently the bottom of a coral sea. It contains a few 

 corals, almost always of the massive forms, though these are not 

 generally disseminated, but occur rather in spots on the sites perhaps 

 of pieces of ancient reef. Occasionally in these collections a branch- 

 ing species may be found, but the small solitary forms are almost 

 unknown. Again, a mass of madrepore is sometimes seen embedded 

 in the matrix and isolated from all companions. Put the great bulk 

 of the rock is a very soft, light, cream-coloured, chalky material, the 

 comminuted debris of coral, ifec, such as is forming at the present 

 day among the coral-reefs of the Bahamas and the Bermudas. The 

 local name of this material in Santo Domingo is caliche. It has the 

 peculiarity that it hardens on exposure to the atmosphere, though 

 not always to the same extent. Usually, in natural exposure, this 

 hardening takes place to a depth of from two to four feet, though 

 often the crust is not more than a foot thick. The indurated por- 

 tion is sufficiently solid for building purposes, though it is almost 

 invariably penetrated in all directions by small cavities, caused 

 partly by the decay of the enclosed fossils." 



He further remarks that " the whole deposit seems to be homo- 

 geneous ; no signs of stratification or difi'erences in degrees of hard- 

 ness being perceptible below the above-mentioned crust. There 

 can be no question but that the greater part is derived from the 

 corals, and the few shells which lived, died, and decayed on the spot." 

 In some places there are " abundance of shells of Ostrcea, Lucina, 

 and of Ve7ieridiv, and casts of Stromhus are nowhere rare." Although 

 it covers such a large area, it does not appear to be anywhere very 

 thick. At Santo Domingo city the bluff is about 40 feet high, but 

 its base is not seen ; the wells in the city average 50 feet deep, and 

 reach to the level of the sea. Farther back, where the ground rises, 

 the wells reach the same level ; two miles N.E. of the city a well is 

 158 feet deep, and another not far off is 170 feet. The surface of 

 the limestone is everywhere covered by a peculiar red soil, which is 

 clearly the result of its decomposition. 



As regards its age, he remarks that it lies unconformably on the 

 late Miocene, and must be either Pliocene or newer. 



(f) Jamaica. — liaised masses of coral-rock appear to fringe a large 

 part of the coast of Jamaica, but little information exists with 

 regard to the occurrence of coral-limestone at higher elevations in- 



