HILL: GEOLOGY OF JAMAICA. 95 
9n 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 
9f old Soboruco some 25 feet in thickness, which is very much consoli- 
dated and erystallized, and resembles more nearly the true white lime- 
Stones than any other exposure of old reef rock seen on the island. It 
i$ mado up almost entirely of coral heads. Three miles west of St. 
argaret 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. 
SEA LEVEL 
Figura 31. Elevated Reefs, Mile Post 97, Coast Road, East of Montego Bay. 
a. Coast Reef. c. Bench of Vertical Richmond Shales. 
b. Grand Plain. d. Old Reef. 
_ About four miles east of Montego Bay there is a fine exposure show- 
Ng two distinct terraces of Soboruco. The older of these is 25 feet 
gh and corresponds to the Barbican terrace. This is a considerable 
distance from the shore bluffs toward the sea; the newer reef merely 
tibs 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 
N the vicinity of the mouth of Great River, Round Hill Point is an 
abrupt, escarpment about 100 feet high. The background is composed 
of Montpelier white limestone. Against this, at a lower level are other 
eds possibly equivalent to the Manchioneal formation, while at the 
°ot of the bluff is a small patch of Soboruco as shown in Figure 32. 
n Hanover Parish, between the mouth of Flint River, twelve miles 
Vest, of Montego Bay, and Lucea Harbor, are the best and most instruct- 
N exposures of Soboruco to be seen around the island. These con- 
“st of three distinct formations occurring at 70, 25, and 5 feet above 
a level. The highest and oldest of these is well exposed at the 18 
“lo Post from Montego Bay, near Hopewell (see Figure 28) along the 
