Mr. De la Beche on the Geology of Jamaica. 159 



lowish and decomposed sandy rock occur in the vicinity of the above lime- 

 stones both at Flamstead and Mount Pleasant. The limestones of the latter 

 place appear to be succeeded for a short distance by sandstones and conglo- 

 merates, resembling those above mentioned. 



Next in order above these appear, nearly opposite the Botanical Garden, a 

 series of shale, schistose sandstone, and more compact sandstone beds which 

 very closely resemble, in mineialogical structure, the coal measures of some 

 parts of England, and the probability of their being such becomes the greater, 

 from the circumstance that thin seams of coal are observed among them. I 

 met with only three of these seams of not more than an inch, and an inch and 

 a half in thickness ; how numerous they may be, it would be difficult to say, as 

 the section presented was of no great size ; yet I do not suspect that there are 

 any beds of this substance that would be worth working for useful purposes. 



The general dip of these beds is to the S.W., sometimes at a considerable 

 angle; they therefore dip conformably with the sandstone and conglomerate 

 rocks on which they seem to rest*. I searched in vain for the vegetable im- 

 pressions, generally termed coal plants, from being found among the true coal 

 measures, which these beds nevertheless very much resemble : they are co- 

 vered by a brownish red conglomerate principally composed of rounded pieces 

 of porphyry, mixed with pebbles of other trap rocks, sandstones, &c., the 

 whole being associated with porphyries and trap rocks. This conglomerate 

 would appear referrible to the same epoch of formation as the rothe todte lie- 

 gende of the Germans. According to some geologists the whole of the rocks 

 here enumerated might be included under the head of red-sandstone {gres 

 rouge), the coal measures being merely subordinate. Humboldt conceives 

 that " le gres houiller et le porphyre constituent une meme formation {rolhes 

 todtes liegende), variable d'aspect, et d'une structure souvent tres-compli- 

 queef;" and D'Aubisson states that " la grande formation de gres houiller se 

 divise tres-convenablement en deux parties; I'une comprend le terrain houil- 

 ler proprement dit ; et I'autre le gres, appele, dans la Thuringe, grhs rouge, 

 avec ses couches subordonnees : mais tout en distinguant ces deux parties, 

 nous remarquerons qu'elles appartiennent a la meme formation ; et quoique 

 le terrain houiller soit le plus souvent au-dessous, il lui arrive quelquefois 

 d'etre entremele, et meme d'etre superpose au gres rouge \." The same au- 

 thor again remarks, that " le gres, masse principale du terrain houiller, prend 



* The beds are continued across the valley of the Hope River, and will be observed forming a 

 cliff near the Botanical Garden. 



t Essai Geognostique sur le Gisement des Roches dans les Deux Hemispheres, p. 205. 



+ Traite de Geognosie, vol. ii. p. 263. 

 VOL. II. SECOND SERIES. Y 



