Mr. De la Beche on the Geology of Jamaica. 157 



Trap rocks occur, as before mentioned, mixed with limestone and grau- 

 wacke, on the first part of the ascent of the Cunha Cunha road from Bath, 

 and in the valley of the Sulphur River between the latter place and the Hot 

 Spring. The trap in these places is principally that last noticed, varying in 

 colour, but not so much crossed by zeolitic veins as on the higher part of the 

 Plantain Garden River. 



Medial or Carboniferous Rocks. 



It is not without some hesitation that I refer the following rocks to this 

 class, particularly as I have only observed the strata, which more immediately 

 lead me to do so, in one place ; these however so much resemble the coal 

 measures of Europe in mineralogical structure, that, though confined to a 

 small place, I conceived it would be better to class them for the present in this 

 order. 



But to commence with the lowest rocks, or those which rest upon the sub- 

 medial country above noticed. On the Southern side of Catherine's Peak, 

 and in the higher part of the valley of the Hope River which descends from 

 it, a series of compact sandstone and conglomerate rocks principally of a red 

 colour, will be observed : there are others which are gray, but they are more 

 or less subordinate to the red. The sandstone varies in texture from extremely 

 hard and compact to rather friable ; the conglomerate also varies in its degree 

 of hardness. 



Under Greenwich Hill a very good section is obtained of these strata, which 

 dip at about an angle of 40° to the S.W., and therefore appear to rest uncon- 

 formably upon the limestones, gray sandstones, and shaly slate of the northern 

 side and summit of Catherine's Peak. The beds vary in thickness from 4 to 

 12 feet, and are almost all red ; the sandstone is mostly siliceous and compact; 

 there are however beds of a marly red sandstone, and marl, insterstratified 

 with the compact sandstones and conglomerates, which latter are composed of 

 rounded pieces of granite (colourless quartz, reddish and white felspar, and 

 black mica), large-grained greenstone, syenite, quartz, hornstone, &c. from 

 the size of a walnut to three or four inches in diameter. These beds with 

 those of slaty sandstone, mixed with beds of compact gray siliceous sandstone 

 seen, on the ascent of the mountain, crowned by Catherine's Peak, seem to 

 compose the lowest part of this formation ; which appears to be of considera- 

 ble thickness, judging from the section afforded by the valley of the Hope 

 River, and, but for the very great difference of dips, would seem to pass into 

 the submedial class. 



But to continue the Hope Valley section. — AtMiddleton House, which I es- 



