100 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
themselves, such as that at Barbican, which can be seen to be clearly 
deposited upon a surface horizontally eroded across the vertical structure 
of the old Blue Mountain Series. Similar submerged plains are now 
occupied by the growing reefs around the island. That these elevated 
reefs were formed on former land surfaces which had been submerged 
and were in the process of emerging, is attested by every topographic 
feature. The streams have cut continuously downward through steadily 
rising old reefs, leaving no evidence of alternating periods of drowning 
between them, such as veneerings of later sea deposits across them. 
Our studies of the Oceanic Series have shown that true reef building 
corals do not occur in the great mass of white limestone composing the 
structure of the back coast country of Jamaica, or at altitudes greater 
than 70 fect. Our paleontologic discussion also shows that the true 
modern reef building coral species first appear doubtfully in the Bowden 
beds, then sparingly in the Manchioneal formation, along the coast be- 
tween Mulatto Bay and Manchioneal and near Round Point, Hanover» 
These and all succeeding beds containing reef coral occur only imme- 
diately adjacent to the present seacoast and unconformably against the 
pre-eroded perimeter of the main area of the island. 
These reefs are laid down on various formations from the Richmond 
shale to the Manchioneal beds, respectively. On the north coast of 
the island they are seen in contact with the Richmond, Montpelier, 
Moneague, and Manchioneal formations, while upon the south gide 
they lie upon the Cobre, Bowden, and Montpelier. 
In general, the old reef rock of Jamaica consists of three distinct for- 
mations occurring at three levels, 70, 25, and 10 feet (or less) respeot- 
ively. From the persistency of these three levels on the north, east, 
and southwest end of the island, it is evident that their present position 
above the water is due to continuous epeirogenic elevation after the 
present outlines of the island had been chiefly defined. 
MiscELLANEOUS COASTAL FORMATIONS CONTEMPORANEOUS IN ORIGIN 
with THE ELEVATED Roers, 
The present land margin is not continuously fringed by growing 
reefs, but they occur in interrupted patches, alternating here and there 
with strips of different kinds of bottom, such as alluvial deposits oP 
posite the mouths of rivers, shell sand, or lagoon mud. Similar com 
ditions prevailed during the time of the creation of the old reefs, and 
hence we find with them many diverse formations of contemporaneouP 
origin, some of which will now be described. 
