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



souvent une grande extension^ en abandonnant, au moins en majeure partie, 

 la houille avec I'argile schisteuse qui Penveloppe^ et il constitue des terrains 

 d'une grande etendue. II a ete principalement observe en Thuringej ou il 

 est connu sous le nom de rothe-todte-liegende *." 



Viewing- these sandstones and conglomerates in the manner of many conti- 

 nental geologists^ they would form one mass with the porphyritic conglome- 

 rate to be mentioned hereafter. Humboldt considers the whole as one for- 

 mation when describing the gres rouge of New Spain^ Venezuela^ New Gre- 

 nada, the plateau of Quito, Peru, and the banks of the Amazon f , which the 

 Jamaica rocks under consideration will be found very much to resemble. 



Dr. Buckland and Mr. Conybeare remark on this subject J, that " in the 

 south-western coal district of England we have three formations of red sand- 

 stone, the newer red sandstone, the millstone grit, and the old red sandstone, 

 all liable to be confounded with one another owing to their prevaiHng red co- 

 lour, and to their containing beds of conglomerate ; and as similar rocks occur, 

 very similarly placed, in various parts of the earth's surface, we find three opi- 

 nions maintained concerning red-sandstone, and each moreover supported by 

 indisputable facts : one that it lies over the coal measures ; another, that it lies 

 beneath them ; and a third, that it is a member of the coal formation." 

 ********** 



" The millstone grit affords the best example in the south-western coal- 

 field of a red sandstone belonging to the coal measures. But occasionally 

 even in this coal-field, and very frequently in the coal districts on the conti- 

 nent, all the coal-grits acquire a red colour ; and for this reason we now find 

 it to be the prevailing opinion among the continental geologists, that the gr^s 

 rouge is a member of the coal formation," 



In fact supposing the red conglomerate occurring between the magnesian 

 limestone and coal measures, the latter and the old red sandstone to come to- 

 gether, the carboniferous limestone being wanting, and the coal-grits generally 

 red, it would be most difficult to say where the one begins or the other ends ; 

 and I consider this to be the case in Jamaica : for although in the valley of the 

 Hope River, the rocks, which I take to represent the coal measures^ do pre- 

 sent a marked appearance for a short space, they seem included among the 

 red sandstones. 



With regard to the other places in Jamaica where I have observed the red 



* Traite de Geognosle, vol. ii. p. 306. 

 t Essai Geognostiqne, &c. 



J In their paper on the South-western Coal District of England : Geological Transactions, 

 New Series, vol. i. p. 314 and 315. 



