SB Mr. De la Becke on [Julv, 



formed by any causes now in action, but tihat the porphyry, 

 greenstone, and other pebbles, which constitute, with a few clay 

 and sand beds, the mass of the plain, were derived from the 

 Jamaica mountains in the same manner, and at the same period, 

 as the numerous European tracts of gravel, which have resulted 

 from the destruction of European rocks, and which contain the 

 remains of elephants, &c. It is true that bones have not yet 

 been discovered in the Jamaica gravels, but it should be recol- 

 lected that the opportunities for such discoveries are by no 

 means so abundant as in those countries where gravels are 

 extensively used for roads ; the climate moreover is such, that 

 few are tempted to risk their health by prosecuting researches 

 of this nature beneath a tropical sun. 



The diluvial plain of Liguanea is continued westward through 

 the low lands of St. Catherine and St. Dorothy ; sands and clays 

 are more abundant in the latter districts, but in other respects 

 the diluvium is the same. The sections afforded by the rivers 

 and gullies are of considerable interest, though I nowhere 

 observed one so deep as that of the Hope River. 



To the westward of the above-mentioned plain, but separated 

 from it by a range of low white limestone hills, is another great 

 plain forming the parish of Vere, and the lower part of that of 

 Clarendon ; it is surrounded by white Hmestone hills and moun- 

 tains* on all sides but on the S and SW, where it is washed by 

 the sea, with the exception of the space occupied by Portland 

 Ridge. 



The greater part of this plain is diluvial, consisting of gravels, 

 clays, and sands; the former is principally composed of porphyry, 

 greenstone, and other trap rock pebbles, which are all most 

 probably derived from the destruction of part of the St., John's 

 and Clarendon mountains. 



Many fine sections of this diluvium are afforded by the Rio 

 Minho, which traverses it nearly through its whole length, as 

 also by numerous deep gullies : it is easy to remark here, as in 

 the case of Liguanea, that the causes now in action tend to 

 destroy this plain, and are altogether inadequate to its formation. 



It is remarkable that though this diluvium is nearly surrounded 

 by hills and mountains of the white limestone formation, very 

 few fragments of it are to be discovered in the gravel, arising 

 probably from its being less hard than the porphyry and green- 

 stone, and, therefore, less able to resist apy violent attrition 



than the latter. < r, . 



)i UK' 111 ■ .; . 



♦ It is sufficient at pTeseni'toSoiterve, that tlic Jamaica white "limestone fomaation 

 consist* of compact white Jimestone beds, resembling the compact varieties of the Jura 

 linaestone ; these beds are often of very considerable thickness, and are associated wkh 

 softer limeKtones (even in some places resembling chaljc), white marls, and thick beds of 

 red sandstone arid marl. The whole formation cannot be less than 2000 feet thick in 

 somCiplaces, and contains fossils, which are, howoverj verfnure in,^ dt « tertiary 

 character, 5Uch as cones, ceritliia, nummulites, &c. f' i . \ r - •*• f^* V' 



