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



maica^ I shall proceed to enumerate the different rocks, commencing with 

 those of the oldest formation. 



SUBMEDIAL OR TRANSITION RoCKS. 



Rocks which may be referred to this class compose the principal portion of 

 the Blue Mountain Range, and are continued in a North-east direction through 

 the parish of St. George into that of St. Mary. They are the oldest rocks 

 which occur in the part of Jamaica examined by me : and from the informa- 

 tion which I have obtained, there does not appear to be any rock of equal age 

 in the other or western portion. The boundary lines of these rocks may be 

 described, commencing with St. Mary's, as forming the whole of the coast of 

 the latter parish, eastward from the mouth of the Agua Alta or Wag Wat^r 

 to within a mile or two of Ora Cabessa Bay, with the exception of Jack's Bay, 

 Don Christopher's Point, Blowing Point, Forster's Cove, Green Cove, Pagee 

 Point, Fort Haldane, and the small island opposite Port Maria ; in all which 

 places the submedial rocks are covered by a part of the white limestone for- 

 mation to be mentioned hereafter. The latter formation rests upon and bounds 

 the above rocks in the vicinity of Eden estate near Ora Cabessa. From 

 thence, after crossing a hill, the line passes at the foot of the high white lime- 

 stone hills that rise above the submedial country in the neighbourhood of the 

 Union and Ramble estates ; and afterwards passes at the base of a continua- 

 tion of the above high land to the vicinity of Unity and Non-Such estates. 

 From the latter point the line is continued a little to the south of Konigsburg, 

 and crosses the Agua Alta to the north of its confluence with the Ugly River; 

 — in this part of its course the submedial country is covered by red sandstone 

 and conglomerate. 



Quitting the parish of St. Mary, the southern boundary line of these rocks 

 crosses the mountains which separate the Agua Alta from the Buff Bay River 

 to the northern face of Catherine's Peak, then enters Port Royal parish, fol- 

 lowing the course of the Yallahs River for some distance, and afterwards, 

 skirts the base of the Blue Mountain Range through St. David's to Bath in 

 St. Thomas-in-the-East. From the latter place, round the coast, to Port An- 

 tonio, the submedial country is separated from the sea by the white limestone 

 formation, except near the latter place, where poi-phyry intervenes between 

 them. 



From Port Antonio to Annotto Bay the northern boundary line of these 

 rocks passes at some little distance from the coast through the parishes of 

 Portland and St. George, gradually approaching the sea as it reaches Annotto 



