1G2 Mr. De la Beche on the Geology of Jamaica. 



tique sur le Gisement des Roches," (p. 157,) and divides it from the grhs rouge 

 of the French and the roihe iodte Uegende of the German geologists^ to which 

 latter rock an eminent British geologist considers it should be referred*. 

 A short distance to the south of Scot's Hall (Maroon Town) these sandstones 

 and conglomerates disappear, and are succeeded by trap rocks ; their dip 

 varies, but is principally to the southward ; I observed it once S.E. on the 

 elevated land where these beds pass into grauwacke. 



At Green Castle, situated on a mountain a short distance westward from 

 Scot's Hall (Maroon Town), these red sandstones and conglomerates are well 

 exposed, as also between Green Castle and Konigsburg estate. The conglo- 

 merates in these places are principally composed of rounded pieces of trappean 

 rocks, and among the latter are greenstones and beautiful porphyries: the beds 

 dip at about 45° to the S.W. near Green Castle, but they are nearly perpen- 

 dicular not far from the same place. On the road to Konigsburg the strata 

 dip in some places to the N.W. Among the contents of a conglomerate bed 

 near Green Castle House, 1 found a rolled agate and a rounded piece of green 

 carbonate of copper. 



A considerable number of porphyry pebbles are found in the conglomerates 

 on the banks of the river by which the road passes from the Green Castle to 

 Konigsburg; this causes the rock more to resemble the red conglomerates of 

 Teignmouth, &c. in Devonshire, than old red sandstone; yet as porphyries 

 are much mixed with those Jamaica rocks that are inferior to it, more parti- 

 cularly in the Blue Mountain district, there seems no reason why rolled pieces 

 of that substance should not occur abundantly in these conglomerates, which 

 rest on them. 



A passage of these rocks into the grauwacke-looking rocks of St. Mary's 

 will be observed near Konigsburg, where the red beds become extremely 

 marly, and pass into a gray shaly slate much mixed up with the grauwacke of 

 St. Mary's. After all there may be a mixture of rothe todte Uegende and old 

 red sandstone in this district, between which it would be almost impossible to 

 distinguish. 



* The term new red conglomerate is no doubt a bad one for the red conglomerates that occur 

 between the coal measures and the magnesian limestonCj as it would seem to imply a connexion, 

 with the new red sandstone (the bunter-sandstein of the Germans, and gres bigarrs of the 

 French); now the latter and the red conglomerates in question are separated by the whole mass 

 of the magnesian limestone {calcaire alpin^ alpenkalkstein), and therefore constitute two sepa. 

 rate formations, which may however come together, the magnesian limestones being wanting, as 

 is probably the case in Devonshire : indeed the red conglomerates of Exeter bear so much resem- 

 blance to the German rothe todte Uegende that I should propose the name of Exeter conglo. 

 meratCj as the English equivalent to the latter rock. 



