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



from this place, but should conceive that it must be of the Anthracite kind. A 

 similar substance, I was informed, had been found at Guatamala upon the Cave 

 River, which flows into the Swift River, but in what rock it would be difficult 

 to say, for there are beds of red-sandstone at that place as well as the lime- 

 stone and marly beds, which cross over from the Buff Bay River. The latter 

 rocks are exposed to view on the Swift and Great Spanish rivers ; and the 

 iron pyrites found among them on the banks of the former have been mistaken 

 for gold. 



Submedial limestones occur occasionally on the southern side of the Blue 

 Mountain Range from the head of the Yallahs River to the neighbourhood of 

 Bath, in St. Thomas-in-the-East, sometimes associated with sandstones and 

 slates having a grauwacke appearance ; at others, with greenstones, syenites, 

 and other trap rocks, in a singular manner. 



Thin beds of compact gray blue limestone are seen connected with slaty 

 shale in the vicinity of Clifton (near Catherine's Peak) ; these dip at an angle 

 of45°totheE.N.E. 



The Green River which falls into theYallahsRivernearGreen Valley Works, 

 brings down, in its course from the Cold Ridge, a considerable quantity of 

 compact grayish blue limestone, which shows that this rock occurs in this part 

 of the Blue Mountains*. Blueish-gray limestone may also be observed neap 

 Green Valley. 



Abbey Green, St. David's, situate on the southern side of the Cold Ridge, 

 is one of the highest coffee settlements in Jamaica : the house upon it I make 

 by barometrical measurement to be 4233 feet above the level of the sea. At 

 this place submedial limestone of a gray colour, and traversed by veins of cal- 

 careous spar, will be found associated in a rather singular manner with syenite^ 

 greenstone, grauwacke, and argillaceous slate, the superposition of one above 

 the other being very indistinct ; so that little can be learned from this spot, 

 which would, if a better section were affijrded, be highly interesting in a geo- 

 logical point of view, as the limestone is here seen close to the trap rocks, and 

 does not appear, from what is exposed by section, to have suffered much if any 

 alteration. 



Not far from Portland Gap (a depression in the Cold Ridge which I esti- 



* The meeting of the debris of the Yallahs and Green rivers is singular, and strongly reminded 

 me of the effect produced by the meeting of the Rhone and Arve near Geneva, where the blue 

 waters of the one and the discoloured glacier waters of the other do not immediately mingle, but 

 flow side by side for some distance : so it is with the debris brought down by the two Jamaica 

 rivers; that of the Green River is blueishfrom the slates, limestones, &c. which it traverses, and 

 that of the Yallahs River reddish, from the red-sandstones and conglomerates which it washes. 



