hill: geology of Jamaica. 



97 



Another type of old reef rock is seen near Barbican, some three miles 

 east of the foregoing locality, in an excellent exposure. This is similarly 

 situated relative to the road and sea as the Hopewell Keef, and likewise 

 occurs unconformably upon the black Richmond shales, here having a 

 dip of 45 degrees. This old reef, which we term the Barbican forma- 



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Figure 34. Elevated Reef and Profile near Barbican. 



1. Caribbean Sea. 



2. Low coast plain five feet above sea, and 200 yards wide. 



3. The Barbican Reef. 



4. A bench 70 feet above sea, occupying the level of the Hopewell Reef. 



5. Back coast country, largely composed of the vertically tilted Richmond Beds 



of the Blue Mountain Series. 



tion, is only three feet in thickness, and is largely composed of a species 

 of coral having an elongated cylindrical or club-like form, and a concen- 

 tric arrangement of its layers. Figures 34, 35, and 36 show the occur- 

 rence of the Barbican reef and its relations to the adjacent topography. 

 The juxtaposition of the Hopewell and Barbican reefs and the lowest 

 coast terrace relative to each other are well shown in the topography 



Figure 85. Relation of Barbican and Older Reef near Mosquito Cove. 



adjacent to Mile Post 19, displaying three distinct benches or terraces 

 against the mountainous back coast country. 



Immediately at Barbican the Barbican terrace, or twenty-five foot 

 level, approaches close to the sea and overlies a fossiliferous sinter 

 or marl which is exposed at the foot of the escarpment, and which is 

 full of molluscan fossils resembling those of the Falmouth formation. 



VOL. XXXIV. 7 



