Mr. De la Beche on the Geology of Jamaica. 181 



marl contains corals, spines of Echinites, and Terebratulse, besides casts of 

 other shells. Throughout the whole of this coast the white marl is the pre- 

 dominating- member of the formation ; and most of the low points, which are 

 numerous, contain an abundance of corals, which have almost a recent ap- 

 pearance when fractured, resembling those formerly mentioned as occurring 

 at Forster's Cove (St. Mary's). The dip of this limestone and marl is either 

 E., N.E., or N.N.E., according to its bearing with the interior of this part of 

 the island round which it mantles. 



On the eastern side of Turtle Crawle Bay a sandy and chalky rock is 

 worked for building-stones, which are used at Port Antonio ; the white lime- 

 stones and marls of which latter place rest upon porphyry. 



From Port Antonio to Burlington (near the mouth of the Rio Grande) the 

 coast is formed of white limestone and marl, the latter being sometimes sandy ; 

 the beds of the former dipping northerly at the cliffs near the ford over the 

 Rio Grande. 



Good sections are afforded of this formation in St. George's by the Swift, 

 Great Spanish, and Buff Bay rivers. It extends up the former to Eden 

 estate ; and both sides of the river present line cliffs of the rocks under con- 

 sideration. The white limestones extend up the Great Spanish River to 

 about half a mile or more above Skibo, the beds varying in thickness, and 

 being contorted near the latter place. The road from Canewood to Low 

 Layton estate, between the mouths of the Swift and Great Spanish rivers, is 

 upon white sandy marl and limestone ; but to the northward of Lennox, and 

 rising above Low Layton the country is composed of volcanic rocks. 



This formation continues up the Buff Bay River for about a mile above 

 Charles Town, the beds varying in thickness and dipping northerly, being 

 however curved in some places. The hills that back the low flat, between 

 Annotto Bay and Buff Bay are composed of white limestones and marls ; the 

 extent of country occupied by them between the sea and the older rocks gra- 

 dually becoming narrower as we approach the former place. In one spot 

 between these two villages, I found nodules of chert in the white marl, from 

 which circumstance it appears probable that the loose pieces of chert scattered 

 over the surface in some parts of St. Mary's parish, as for instance in the 

 neighbourhood of Islington estate, and in the diluvial soil between Unity and 

 Non-Such estates and Port Maria, may have been derived from the destruc- 

 tion of some beds of the white limestone formation: and this supposition is 

 rendered more probable by finding pieces of compact white limestone scat- 

 tered over the surface of the submedial or transition country between Non- 

 Such estate and Port Maria. 



