76 Geology of Antigua. 
Antigua is a little north of the centre of the circular segment 
of islands, which bound the West India Archipelago on the east. 
It is in north lat. 17°, and west long. 62°, and coniprises an area 
of one hundred and eight square miles. 
‘The trap formation commences on the southeast corner, and in-. 
cludes nearly one quarter of the island. The district is broken. 
and mountainous, rising occasionally into summits of eight hun-. 
dred or one thousand feet in height, some of which are bold and 
precipitous, and others more gentle and rounded, affording a luxu- 
riant soil for cultivation. It is also divided. by valleys, which in- 
tersect each other in different directions, and are beautifully man- 
tled by a rich and ever-blooming vegetation. The rocks are con- 
siderably diversified. Basalt, in extremely distinet globular con- — 
cretions, is not uncommon. Indeed, I saw concretions so perfect, 
that ps might justly be compared to piles of cannon balls from. 
three to six inches in diameter. In some instances, the. interior 
was decomposed, and the concretions were presented in the form 
of well defined and regularly arranged cups imbedded in the sut-_ 
face of the rocks. Breecias and porphyry are very common. 7 
The latter is often of a comparatively light porous character} 
and, at a little distance, might easily be mistaken for red sand- - 
stone. ‘The matrix has a red earthy appearance, and the imbed- : 
ded feldspar and scoriz are soft and easily decomposed. -Drew’s — 
Hill is.composed principally of a rock of this description. Brec- 
cias, of an exceedingly hard and compact character, are not un- . 
frequent. . L often saw them in the form of boulders, at consid- 
erable distances from their beds. Genuine greenstone, of a nearly 
homogeneous aspect, also occurs, and is sometimes employed for 
macadamizing the streets of St. John’s, These roeks overlie, 
and are protruded among the stratified rocks of the contiguous 
formation in every possible manner. Not unfrequently one is 
enveloped in the other ; and both are so blended and changed by 
having been suddenly brought in contact in opposite states of 
heat, that the line of separation can scarcely be perceived with- 
out examining their composition. At Drew’s Hill, a vein of la- 
mellar sulphate of barytes occurs in this formation; but of how 
great extent it is not easy to decide from the excavations which 
have yet been made. : 
This group i is separated from the clay Seameabicia on the north- ‘4 
east, by what are called the Body Ponds, and by a small stream 
