hill: geology of JAMAICA. 



99 



The foregoing descriptions of the Soboruco practically include all locali- 

 ties studied by us, except the coast adjacent to Savanna-la-Mar. The 

 observations include points around the entire perimeter of the island 

 except the extreme west coast and the south coast west of Kingston. 



Figure 37. Cross Section, West Side of Lucea Harbor. 



a. Soboruco. 



b. Elevated Reef. 



c. Folded Richmond Beds. 



Those portions of the coast not seen by us have been sufficiently de- 

 scribed and mapped by the official surveyors to show that the Soboruco 

 occurs at many points in them. From Brown's description of West- 

 moreland^ it is evident that the ten foot or coast Soboruco, and the 

 twenty-five foot or Barbican Soboruco, are each represented there at a 

 different locality, the former between Scott Cove and White Hill Point, 

 and east of Homer Cove, and the latter at South Negril Cliff. The 

 same author^ describes, in a general way, the Soboruco in St. Elizabeth, 

 where it forms low cliffs 15 or 20 feet high and rests upon the "White 

 Limestone." He ascribes it to a Post-Pliocene age. No definite men- 

 tion is made of this formation along the coasts of Manchester or Claren- 

 don (Vere) by the Jamaican geologists, although it is placed upon the 

 map by them. 



Conclusions concerning the Elevated Reefs and the History of 

 Reef Building Corals in the Jamaican Sequence. 



The old reefs grew upon marginal benches or terraces, which previous 

 to their submergence were probably wave-cut constructional or grada- 

 tional plains like those now seen upon the land configuration. As they 

 successively rose during subsequent elevation to within 20 fathoms or 

 less, the zone of coral growth, they were occupied by the polyps which 

 constructed the reef which has since been elevated into land. 



That Jamaica was once a more extensive land than now, with benched 

 and terraced margins which were submerged by subsidence, is shown not 

 only by the adjacent submarine configuration but by the elevated reefs 



1 Jamaican Reports, p. 228. 2 Qp cit., pp. 208, 209. 



