1818.] ON THE FORilATION OF ROCKS- m 



the counties of Yorkshire, Lancashire, Cheshire, and 

 in fact, the greatest part of the coals wrought in Eng- 

 land, with the exception of some fields in Wales, 

 which are in primitive basins ; the coals in Poland, ou 

 the foot of the compact limestone of the Carpathian 

 mountains, through Silesia, and following the calcare- 

 ous chain through Germany to the Hartz ; the coals at 

 Aix la Chapelle and Liege ; and perhaps all the coals 

 in Flanders, may be found to repose in calcareous ba- 

 sins, or to crop out at the foot of calcareous hills. The 

 immense beds of coal lying upon secondary limestone 

 west of the Alleghany mountains in North America, are 

 likewise of this description. This is, perhaps, the 

 most extensive and regular of the coal formations ; the 

 beds are generally of a moderate thickness, or from 

 one to six feet 5 of great extent ; a great number lying 

 ■one under the other, even to SO or 30 beds 5 and alter- 

 nating principally with slaty clay and sandstone, with 

 little or no Puddingstone. The argillaceous Ironstone 

 so frequently wrought as an iron ore in England^ is 

 found in beds of clay in this formation. 



The second repository or deposit, is found in the 

 hollows or valleys iu the primitive formation, such as 

 the coals near Nant?^, on the Allier, St. Etienne, and 

 Hive du Guir, in France 5 Richmond, in the United 

 States of America, &c. &e. These deposits are gene- 

 rally less extensive than the first ; they are in clusters 

 or heaps of 40 or 50 feet thick, without any regularity 

 in the stratification ; often after working a 40 or 50 feet 

 bed, it runs out to a thread in 50 or 100 yards, and re- 

 commences in another place. They alternate with, and 

 are covered by, a great proportion of Puddingstone, and 



