Geology of Antigua. 81 



are found only in rocks of the chert family, which is a very im- 

 portant circumstance in ascertaining the origin of the beds. 



As I have already intimated, the two preceding formations 

 abound in the silicious fossils of an exceedingly interesting and 

 important character. For variety of structure, for fineness and 

 beauty of material, and for richness of color, I know of none in 

 any part of the world in comparison with which they would 

 suffer. They are found in the form of jasper, cornelian, agate, 

 chalcedony — sometimes existing separately, at others all beauti- 

 fully blended in the same specimen. The coloring matter also 

 varies in intensity, presenting every tint and shade which are pe- 

 culiar to those minerals. But the most striking feature of all, 

 is the perfect preservation of the form and structure of the petri- 

 fied substances, even of such as in a living state are most delicate. 

 For example, the opening leaves of the banana, than which no 

 vegetable fibre can be more tender, have been converted into 

 silex and perfectly preserved. I saw myself the petrified pod of 

 a tamarind, so entire in its shape and all its parts, that no one 

 could mistake it. 



These fossils may conveniently be divided into two classes — 

 the marine and the land fossils. The former consist of corals, 

 shells, &c., which are found principally in the calcareous forma- 

 tion, and are particularly abundant and beautiful in Belfast Divis- 

 ion. They frequently appear on the surface, but are often found 

 at considerable depths. The corals are frequently very striking ; 

 they are converted into chalcedony both pure and colored, but 

 still retaining their pattern so perfectly, that the genus may be 

 recognized when they are set in a breastpin. All the fossils in 

 the calcareous formation are by no means of this character. 

 Many of them are calcareous. The silicious prevail only in 

 particular districts. 



But the most interesting class of fossils is the silicified wood — 

 the ordinary trees and shrubs of the climate still retaining their 

 individual structures, but converted into the choicest mineral sub- 

 stances. Fossils of this class are confined to the chert and clay 

 formations. They are generally found intermingled with the 

 chert in broken fragments, and scattered over the surface of the 

 earth. Sometimes in low districts, they constitute immense beds, 

 and give one the idea of a thick forest, which has been prostra- 

 ted by some mighty tempest, converted into silex, and buried be- 



VoL. XXXy.— No. 1. 11 



