160 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
shape. This constituted a gently arched openly folded anticlinal struc 
ture, inclining north and south. This broad fold is marked in its 
course by numerous short secondary wrinkles or miniature low anticlinal 
p folds, as is so beautifully shown in many places, notably near Catadup 
i and Montpelier, (See Figs. 18, 19, 20.) 
| Accompanying this uplift was a great intrusion from below of the deep 
seated granitoid and dioritic rocks we have described. The central 
4 location of this mass below the limestone, now so beautifully exposed 
by subsequent erosion in St. Mary, the metamorphism which the over- 
lying Montpelier beds have suffered, and the numerous dikes protruding 
j] from it through the oceanic limestones and Blue Mountain Series, indi- 
ate that this laccolith was contemporaneous with this epoch, and co!“ 
roborate the belief that, if it was not the direct cause, it was at least 
intimately associated with this Mid-Tertiary apmemeene!) uplift of 
Jamaica. 
The higher terraces or levels, between 1,000 and 2,100 foot, seem t0 
have been during or immediately following this emergence epoch, à! 
previous to the next subsidence to be described. We shall also shoW 
that this event was not peculiarly Jamaican in its effects, but had 2 
wide reaching influence in Antillean and Central American geography: 
The next event in Jamaican history was a renewal of subsidence a” 
a contraction of the land to its present back coast borders, This sub“ 
sidence, recorded in the Bowden formation, involved at its conclusio? 
only the margins of the present island area, which at its beginning was 
probably expanded beyond its present borders. It was initiated by the 
deposition i the land derived littorals of Bowden gravels, found only 
in the north and south coasts of the eastern portions of the island, 4” 
probably culminated in the deposits of the shallow marls. The ampli 
tude of this movement was probably less than one third that of th? 
great Montpelier subsidence. The Bowden and Cobre beds enorus? 
the pediments of the island up to a height of less than 300 feet. yu 
land area during this epoch again became insular in character.! 
nt 
| Succeeding the Bowden epoch there was another upward moveme 
of the island. The larger portion, which had remained land durir i 
] the 
Bowden subsidence, including much of the Limestone Plateau ant 
is]an! d, 
qicat? 
jon; 
1 The probable absence of these formations from the western half of the 
if true, and the immediate east coast if proven after further researeh, may inc 
that the Jamaica-Haiti land connection continued to exist during their deposit! 
and that the more extensive lands existed to the south and west in the vicinity ? 
the Pedro Banks or beyond. 
| 
4Y 
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