36 Outlines of Geology. 



logical Transactions, by Messrs. Buckland and Conybeare, may 

 be referred to as the best geological history extant of these im- 

 portant formations. 



The great northern coal-district of England lies between the 

 river Tees (which separates Durham from Yorkshire,) and the 

 Tweed, and the country slopes from Crossfell and the Cheviots 

 slowly towards the sea, the abrupt faces of those hills being upon 

 their western side. The beds of which this coal-field consists 

 partake of the general slope of the face of the country, reaching the 

 surface on Crossfell, and gradually dipping towards the east, and 

 away under the sea. At Sunderland they are covered by magne- 

 sian limestone, and they appear to lie in a basin of mountain lime- 

 stone, abounding in veins of lead. . . 



The strata of the coal-basin are coal, sandstone, shale, lime- 

 stone, and basalt, and they abound in vegetable impressions and 

 in fresh- water shells ; among the former, the varieties of fern 

 predominate ; among the latter, bivalves like those of the fresh- 

 water muscle. It may not be improper here briefly to notice the 

 chemical varieties of coal that are presented to us in these dis- 

 tricts, especially as relating to their economical applications. 



The coal which is generally most esteemed is that of the' nor- 

 thern districts, Northumberland, Durham, and Yorkshire; it 

 abounds in bitumen, softens in the fire, swells, and throws out jets 

 of flame ; it coheres, and therefore burns hollow and requires 

 poking ; it furnishes cinders, though but little ash. On the other 

 hand, most of the coal from the west of England blazes and burns 

 briskly, being much more easily kindled than the other ; it requires 

 no poking, because it has no tendency to cake ; it affords no 

 cinders, and leaves a dusty white ash. 



A third kind of coal called culm, or stone-coal, contains scarcely 

 any bitumen, and abounds in earthy matter ; it is very difficult of 

 inflammation. Besides these, there are some other varieties, such 

 as cannel-coal, splent-coal, fyc. 



There is one important circumstance observable in stratified 

 countries in general, already adverted to, and more especially 

 shown in the coal-beds, which is, that they were evidently depo- 



