HILL: GEOLOGY OF JAMAICA. 



95 



on the official geologic map), and nowhere does it stand over ten feet 

 above the sea or extend back from it over a few yards. 



Near Orange Bay east of Port Maria the railway cuts through a mass 

 of old Soboruco some 25 feet in thickness, which is very much consoli- 

 dated and crystallized, and resembles more nearly the true white lime- 

 stones than any other exposure of old reef rock seen on the island. It 

 is made up almost entirely of coral heads. Three miles west of St. 

 Margaret Bay there is a bluff of very old looking Soboruco, standing 

 35 feet above the sea. Between St. Ann Bay and a point within four 

 miles of Montego Bay, the coast plain for the most part consists of the 

 beds of white marl elsewhere described as the Falmouth formation, al- 

 though occasional patches of Soboruco are seen immediately bordering 

 the sea, standing about five feet above mean tide level. 



5£A LEVSTL 



Figure 31. Elevated Reefs, Mile Post 97, Coast Road, East of jNIontego Bay. 

 a. Coast Reef. c. Bench of Vertical Riclimond Shales. 



h. Grand Plain. 



d. Old Reef. 



About four miles east of Montego Bay there is a fine exposure show- 

 ing two distinct terraces of Soboruco. The older of these is 25 feet 

 high and corresponds to the Barbican terrace. This is a considerable 

 distance from the shore bluffs toward the sea ; the newer reef merely 

 tips the coast at the sea margin, and is only five, feet above it. There 

 are several patches of the lowest Soboruco at the town of Montego Bay 

 and on the western portion of the bay before reaching Round Hill Point 

 in the vicinity of the mouth of Great Piver. Pound Hill Point is an 

 abrupt escarpment about 100 feet high. The background is composed 

 of Montpelier white limestone. Against this, at a lower level arc other 

 beds possibly equivalent to the Manchioneal formation, while at the 

 foot of the bluff is a small patch of Soboruco as shown in Figure 32. 



In Hanover Parish, between the mouth of Flint Piver, twelve miles 

 west of Montego Bay, and Lucea Harbor, are the best and most instruct- 

 ive exposures of Soboruco to be seen around the island. These con- 

 sist of three distinct formations occurring at 70, 25, and 5 feet above 

 sea level. The highest and oldest of these is well exposed at the 18 

 Mile Post from Montego Bay, near Hopewell (see Figure 28) along the 



