Mr, De Ja Beche on the Geologi/ of Jamaica. 161 



sandstones and conglomerates, the map will express better than words, the 

 space occupied by them ; I shall therefore only offer remarks on those places 

 where sections may in some measure be obtained. 



Upon the summit of St. George's Gap thick beds of red sandstone are ob- 

 servable, which with numerous similar beds interstratified with red conglome- 

 rates dip to the S.W. on the southern side of the mountain ; and, as before 

 observed, strata, which bear considerable resemblance to these, are found as- 

 sociated with the submedial rocks on the northern face of the same mountain : 

 this circumstance would make it appear probable that the red sandstone passes 

 into the grauwacke, if it were not for the very sudden change of dip in the 

 two red sandstones on both sides of the mountain. 



Descending from St. George's Gap to the Kingston plain on the south, 

 beds of red sandstone and conglomerate are met with, precisely resembling 

 those that occur on the Hope River, of which indeed they form the continua- 

 tion, St. George's Gap being part of Catherine's Peak ridge. These are 

 succeeded and covered by a light-coloured sandstone, most probably the same 

 that occurs near the limestone and coal measures on the Hope River, I did 

 not however perceive any of the latter rocks on the descent from the Gap. 



The Agua Alta or Wag Water presents a section of red sandstones and 

 conglomerates, which would appear to be a continuation of those above de- 

 scribed, and which are particularly interesting, as an evident passage takes 

 place between them and the grauwacke sandstones and conglomerates of 

 St. Mary's. The road from Annotto Bay to Scot's Hall (Maroon Town) tra- 

 verses some elevated land in order to avoid a great bend in the Agua Alta, 

 where the Ugly River flows into it. The grauwacke which is here princi- 

 pally composed of thick conglomerate beds contains a few strata of a red co- 

 lour; these afterwards become more numerous to the exclusion of the gray 

 beds ; slaty beds of the latter colour may however be occasionally observed 

 among the red sandstones some little distance to the south of the elevated 

 land. These rocks therefore seem to pass into one another; in fact the 

 change is at first scarcely more than that of colour, the component parts of 

 the gray and red beds closely resembling each other. 



The lower beds of old red sandstone sometimes graduate (as is well 

 known) into grauwacke upon which it reposes ; therefore, if the St. Mary's 

 rocks be considered as grauwacke, we may not unfairly conclude that the 

 sandstones and conglomerates of Scot's Hall (Maroon Town) represent the old 

 red sandstones of the English series. From the circumstance of old red sand- 

 stone passing into grauwacke it is usual for continental geologists to consider 

 it as a variety of the latter rock : Humboldt does so in his " Essai Geognos- 



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