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 comprises 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 distinct globular con- 

 cretions, is not uncommon. Indeed, I saw concretions so perfect, 

 that they might justly be compared to piles of cannon balls from 

 three to six inclies 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 sur- 

 face of the rocks. Breccias and porphyry are very common. 

 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 scoriae 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. I 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 rocks 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 is separated from the clay formation on the north- 

 eastj by what are called the Body Ponds, and by a small stream 



