78 Geology of Antigua. 
character of a conglomerate, but are much less inclined, and 
have been less subjected to heat. 
_ The remaining formation is the calcareous. It is far the most 
extensive of the three, and comprises the north and northeast 
parts of the island. “It is no where very elevated—the highest 
hills not rising more than 300 or 400 feet above the level of the 
ocean. The surface of the ground is generally undulating } 
sometimes the hills are abrupt and broken, having summits cov- 
ered with a light soil and overgrown with tropical shrubs, partie- 
ularly Lantana involucrata, Pisonia subcordata, and Croton bal- 
samiferum. ‘The slopes of the hills and the lower grounds are 
highly cultivated; and, in an agricultural point of view, consti- 
tute the best portion of the island. This formation is separated 
from the preceding by a low tract, extending from Dickinson’s 
Bay to Willoughby Bay, which Dr. Nicholson thinks was, at no 
very remote period, submerged, and divided the island into two 
nearly equal parts. - 
The composition of this formation, like that of the correspond- 
ing one in St. Croix, is by no means uniform. In many places, 
it consists of marl, which may be easily quarried with a heavy 
hoe’; in others, it isa tolerably compact limestone which can be 
broken only with a hammer. I did not observe any specimens 
of what I called “coral erag” in the geology of St. Croix, though 
further observation might have brought them to light. Dr. Nu- 
gent describes strata running through the marl, which TI had not 
an opportunity to see, “ consisting of a grit stone, divisible into 
thin layers,” and appearing under a magnifying glass to be “ madé 
up of very minute fragments of quartz, hornblende, jasper, horn- 
stone, and green earth, held together by an argillaceous cement.” 
It also contains localities of a yellow calcareous sandstone, break- 
ing with an earthy, conchoidal fracture, and employed extensively 
in architecture. Asa group, this formation is stratified; but, in 
‘many places, the planes disappear, and the mass bears the aspect 
of a precipitate from water. Though it obviously rests upon the 
clay, the strata of the two formations are not conformable ; those 
of the marl being sometimes horizontal, and at others inclined in 
different directions. 
: _ This formation contains a great variety of fossils. “ Of these 
we many “soem says Dr. Nugent, “as most frequently pre 
enting themselve aces “species of madrepore, echinus, se!- 
6 | 
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