THE VICINITY OF THE HAVANA. 193 



On the north side of the excavation the vein is solid ; having a thick- 

 ness gradually increasing to four feet. 



The coal is formed in parallel layers of from one to four inches in 

 thickness. Sometimes these layers, instead of being perfectly horizon- 

 tal, are slightly curved, especially towards their extremities. This is 

 particularly the case where an accidental derangement has taken place 

 in the vein. On its sides, near the walls of the vein, the coal for a 

 few inches in breadth is deflected, as if it had been pressed by the 

 sides or walls. Here the structure becomes baccillary, and the coal, 

 on the slightest effort, divides into irregular polyhedrons. The surface 

 of this coal, when detached from the walls, instead of being smooth, or 

 covered with any kind of bituminous shale, is rough, and presents a 

 baccilo-fibrous appearance, similar to the structure observed in arrago- 

 nites and other fibrous minerals. Two or three small branches, or 

 filons, are seen passing from the main vein at about the depth of twenty 

 feet, occupying smaller fissures in the rock. 



On the south side of the opening, the coal, in rising towards the 

 surface, parts off into two separate veins, and is apparently more dis- 

 seminated through the rock than on the north side, as may be seen in 

 the ground plan accompanying this article. 



We have here, in the strictest sense of the word, a coal vein, and 

 unlike any we have before witnessed in any part of the world ! It is 

 distinguished from the ordinary deposites of coal, inasmuch as they 

 occur in distinctly stratified beds, and almost invariably exhibit abun- 

 dant traces of organic remains, for the most part of vegetable origin : 

 whereas we have here before us what was evidently, originally, an ir- 

 regular open fissure, terminating above in a wedgelike form, having 

 various branches, all of which have been subsequently filled with car- 

 bonaceous matter, as if injected from below, and that not by slow de- 

 grees and by an infinite succession of depositions, but suddenly and at 

 once. 



This coal is wholly unaccompanied by traces of vegetable remains, 

 or by the beds of bituminous or other shales, which almost invariably 

 envelope or accompany ordinary coal seams, whether in secondary or 

 transition formations. The layers, of which we have spoken, are for 

 the most part horizontal ; that is to say, at right angles to the sides of 



