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



inclined plane from Kingston to the base of the mountains on the north of 

 Somerset estate, where a few patches of compact white limestone separate it 

 from the syenite. 



Ascending towards St. George's Gap, the lower mountains are found to be 

 formed of syenite for some distance; to this succeeds a conglomerate composed 

 of porphyry and other trap rock pebbles, having a brownish red argillaceous 

 cement, and occurring in beds of various thickness. The dip being southerly, 

 the conglomerate has the appearance of supporting the syenite. In one or 

 two places I observed greenstone associated with the conglomerate : and 

 beneath the latter there is a light coloured sandstone, similar to that found 

 near the coal measures on the Hope River. This is succeeded by the red 

 sandstones and conglomerates, which may in some measure be considered as 

 equivalent to our old red sandstone : they dip S.W. near the summit of the 

 Gap. Upon the northern descent from this place there are beds very much 

 resembling those of the southern side ; but these latter red sandstones and 

 conglomerates are associated with grauwacke and dip to the N.E. From 

 hence passing down the valley of the Buff Bay River, we find that all the 

 rocks dip more or less to the nortiiward, while those on the south of the Gap 

 dip more or less to the southward. 



The submedial or transition country, which comes in to the northward of 

 St. George's Gap, continues nearly to Charles Town, and is composed of the 

 rocks enumerated under the proper head. Approaching the town the grau- 

 wacke passes into red sandstone and conglomerate, and the latter support the 

 white limestone formation which extends nearly to the sea. 



The section from the sea near Kingston by Half Way Tree, Stony Hill 

 Barracks, and Scot's Hall (Maroon Town), to Forster's Cove (St. Mary's), 

 (Plate XIX. fig. 2. ) exposes nearly the same rocks as the above. The diluvial 

 gravel abuts against the base of Stony Hill, which is composed of the white 

 limestone formation, dipping to the southward. This limestone is separated 

 from the porphyritic conglomerate upon which it rests, by light coloured sands 

 and marls, as may be observed on the descent to the Agua Alta, or Wag 

 Water. These are succeeded by a great mass of various trap rocks, among 

 which I here and there observed ( in the bed of the Agua Alta) some conglo- 

 merate beds, composed of trappean pebbles cemented by a trappean substance. 

 This trap seems to rest upon the red sandstone and conglomerate beds, that 

 pass into grauwacke to the northward of Scot's Hall (Maroon Town). 



From thence grauwacke continues across St. Mary's parish to the sea near 

 Forster's Cove, where some of the upper beds of the white limestone forma- 

 tion rest upon it. 



