HILL: GEOLOGY OF JAMAICA. 98 
Cessive reefs is best shown on the west end of the north coast between 
Montego Bay and Lucea in the parish of Hanover. 
Extensive patches of Soboruco border the coast two miles east of Port 
Antonio. This is made up entirely of large coral heads! and super- 
ficially consolidated into rough jagged surfaces. It forms a low bluff 
about ten feet high, which is being undermined by wave action. It 
9xtends back from the water only a short distance, and numerous in- 
dentations have been cut into it by the sea. "There are similar ex- 
Posures on both sides of Williamsfield Harbor, making the coast line for 
two or three miles. "The horizontal surface of these constitutes a bench 
Against the line of back coast hills, here composed of yellow Pliocene 
Marl, In places in this vicinity the Soboruco is backed “by swamps 
lying between it and the hills. These swamps may have once been 
lagoons attending the landward side of the Soboruco when it was a reef 
in the soa, On Plate XXVIII. is an illustration of the Soboruco bench 
in this vicinity, which shows in the foreground the jagged indurated 
Surfaces of the rock, and in the middle ground and distance the under- 
Mining bluff and wave indented incisions. Plate XXIX. shows the 
Composition and structure of the Soboruco, here made up of large in- 
dividuals of reef making corals. The Soboruco of the east end of the 
island is unconformable upon the Montpelier white limestones, the 
Bowden, and the Manchioneal formations. 
e The straight east coast of the island which extends to Point Morant 
1S reached after passing Northeast Point. At the mouth of Priest- 
Man’s River a cross section exposing the entire thickness of an elevated 
reef is seen on both sides of the river for a considerable distance back 
from. the sen, where it forms a vertical scarp some 25 feet in thickness. 
t overlies the yellow Manchioneal marls in which the present stream- 
Way is situated. This exposure of Soboruco is made up of gigantic 
teef coral heads and its surface constitutes a wide flat bench extending 
from the sea to the back coast mountains. The top of this old reef is 
About 70 feet above the sea, an altitude equal to the level of the Hope- 
Well old reef formation on the west side of the north coast, and the 
Sreatest, height at which any undoubted reef rock is known to occur 
on the island. 
The Priestman’s River terrace extends a considerable distance towards 
Black River. South of the latter as far as Holland Bay its level is 
“ontinued by a baselevelled plain underlain by the older limestones, 
i 1 The species of corals from the localities mentioned are all given in the paleon- 
logic Portion of this paper. 
o S 
