Mr. De la Beche on the Geology of Jamaica. 189 



The section from Old Harbour to Luidas Vale (fig. 3.) shows the connexion 

 of the trap mountains in St. John's with the white limestone formation on the 

 north and south of it. The alluvial and diluvial plain of St, Dorothy's con- 

 tinues to the base of the white limestone hills near the Rectory, which is itself 

 situated upon a small white limestone hill, that rises out of the plain. The 

 white limestone dips southerly, and continues to Wood Hall estate, where it 

 dips from, and apparently rests on, the trap. The latter afterwards forms the 

 mountains to Mount Pleasant, situated on the mountain that rises to the south 

 of Luidas Vale : here the white limestone again comes in, and rests upon trap 

 rocks. The beds now, however, dip at a considerable angle to the north, ap- 

 pearing as if they were forced up into their present position by the trap ; and a 

 glance at the section will show that the trap has very much the appearance of 

 having been protruded through the white limestone formation, which, it will 

 be seen, returns to its southerly dip on the north side of Luidas Vale. The 

 limestone may have been deposited on the trap, though it is somewhat difficult 

 to conceive how strata, inclined like those between Mount Pleasant and Luidas 

 Vale, could have been formed by deposition from a fluid. Geologists are well 

 aware how difficult it is to refer trap rocks to any particular epoch of forma- 

 tion ; I have therefore not attempted to make any distinctions in this respect 

 between the trap of the St. John's Mountains and that extending through the 

 parishes of Port Royal and St. Andrew's, into St. Mary's : in fact, the trap 

 rocks of the two districts very nearly resemble each other ; and, in both cases, 

 appear from beneath the white limestone formation. 



The next section to be noticed is that from the sea, over the Long Moun- 

 tain, and up the valley of the Hope River, to Catherine's Peak (fig. 4.). A 

 sand-bank (the Palisades) protects the branch of the sea forming Kingston 

 Harbour, on the north of which (in our line of section) rises the Long Moun- 

 jtain, composed of white limestone dipping southerly, and separated by a little 

 diluvium from the sea. Between the Long Mountain and the mountain on 

 the north of the Hope estate we meet with part of the diluvium of the Ligua- 

 nea plain. This abuts against the porphyritic conglomerate, which forms the 

 gorge of the Hope River Valley near the Hope Tavern, and is continued up 

 the valley to nearly opposite the Botanical Garden, where the rocks which I 

 have described as resembling coal-measures occur beneath it. To these suc- 

 ceed a red and gray conglomerate mixed with light coloured sandstones, 

 among which a compact gray limestone is found, very much resembling the 

 carboniferous limestone of the English series. Beneath these are the red 

 sandstones and conglomerates which I have stated may be equivalent to our 

 old red sandstones. 



