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



mate from barometrical observations to be 5642 feet above the sea), and on 

 the road to that place from Abbey Green, I found a large block of grayish 

 white limestone approaching the crystalline or saccharine character, and some- 

 what resembling the primitive limestones ; it was however most probably de- 

 rived from some bed associated with the submedial rocks of the district, which 

 is concealed beneath the thick foliage of the tropical forest that rises above 

 the spot where the block is found. 



Sections of submedial limestone are afforded near Bath in St. Thomas-in- 

 the-East : the best is that seen between the village and the hot spring, up the 

 valley of the Sulphur River ; a dark lilac-coloured compact limestone will be 

 there observed connected with trap rocks and argillaceous slate. The Bath 

 mineral spring, (the heat of which I found to be =127° Fahrenheit, the ther- 

 mometer being plunged into the spring itself,) rises from a mixture of argilla- 

 ceous slate and thin beds of compact gray limestone ; trap rocks being how- 

 ever not far distant. 



The first part of the ascent of the Cunha Cunha road from the Plantain 

 Garden River presents a continuation of the beds exposed in the valley of the 

 Sulphur River, a lilac-coloured limestone traversed by veins of calcareous spar 

 being associated with argillaceous slate and trap. Higher up the mountain 

 on the same road, a light gray limestone of very compact texture is seen 

 forming part of the submedial country. 



Argillaceous Slate. — I did not observe that this rock constituted by itself any 

 considerable portion of the submedial or transition country of Jamaica; the 

 variety, commonly called grauwacke slate, occurs however in considerable 

 abundance in the parish of St, Mary, in some places not much mixed with 

 the thick and compact grauwacke beds. 



Argillaceous slate may occupy considerable space in the Blue Mountains, for 

 there were many sections of this range which I had no opportunity of examining. 

 This slate is found not only in those places where this rock has been mentioned 

 as occurring associated with others, but also beneath the white limestone 

 formation on the ridge which separates the Morant from the Plantain Garden 

 River, between Spring and Whitehall estates. It is also seen mixed with trap 

 rocks in the bed of the Plantain Garden River from the latter place to Bath. 



The mass of marly slate which occurs with the limestones from Belcarres 

 on the Buff Bay River to the St. George's Gap Mountain can scarcely in strict- 

 ness be called argillaceous slate, and therefore cannot fairly be classed under 

 this head : it however forms so considerable a portion of country, and is such 

 a conspicuous feature in the geology of this part of Jamaica, that it scarcely 

 deserves to be considered as subordinate to the limestones. 



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