isB ] ON THE FORMATION OF ROCKS. 305 



28. Antliracite being a combustible, and found al- 

 ternating with sills t, having vegetable impressions, 

 though rare, must be considered of Neptunian origin. 

 Two kinds of anthracite have been found within the 

 United States of America , one rather granular, of a 

 grayish colour, and slight metallic appearance, contain- 

 ing small veins of quartz ; the other blacker and more 

 shining, resembling more the common coal in appear- 

 ance. 



Tliis formation in the United States of America, has 

 been generally attended Vt ith a satiny transition slate^ 

 bearing impressions of vegetables, a rather hard spe- 

 cies of allum slate, and strata of black clialk, as in 

 Spain, which is included likewise in transition slate 

 formation ; it has been said to exist in the primitive in 

 some parts of Europe, but in no place where I have 

 had occasion to examine the situation of the anthracito 

 have I found primitive rocks covering or overlaying this 

 formation ^ though in some places they miglit serve as 

 the foundation to it. I have likewise near Edinburgh, 

 in Hungary^ and in France near Tulle, examined 

 the common bituminous coal formation, which was said 

 to alternate, and to be covered, with primitive rocks; but 

 found it only in appearance, from the derangement of 

 the original situation of the strata in both iilaces : 

 agreeably to my observation they were the remains of 

 a coal formation in a primitive valley, which had un- 

 dergone considerable revolutions, so as to leave only 

 ft few diglccatcd fragments of the fermer stratifica- 

 tion. 



