190 ORGANIC REMAINS. 



of various kinds; and several hundred-weights have been sent to 

 Edinburgh and other distant parts, for the same purpose. 



The principal repository of jet is the main bed of alum shale, 

 but it is not limited to the aluminous beds. We found some of it in 

 the second shale near Terrington, and it has been often found in the 

 same bed at Malton. Even the sandstone sometimes contains it; 

 though in that matrix it is generally brittle, and holds a kind of 

 intermediate station between the best jet and coal. In the front of 

 the cliff, on the north-west side of Haiburn wyke, is the petrified 

 stump of a tree, in an erect posture, about three feet high, and fifteen 

 inches across ; having the i-oots, which are in a bed of shale, in the 

 state of coaly jet; while the trunk, which rises in the sandstone, 

 consists partly of common petrified wood, and partly of deca,yed 

 wood, which has a sooty aspect. 



The affinity between jet and coal, particularly what is termed 

 cannel coal, is well known; and having considered jet as a particular 

 modification of petrified wood, we would venture to pronounce coal 

 another of its varieties. As we find specimens of petrified wood 

 consisting partly of jet, so we also find not a few in which there is 

 real coal, breaking into cubical fragments, in the usual form. This 

 is the case, both in large blocks of petrified wood, and smaller 

 pieces. The coal occurring in such specimens, whether imbedded 

 in the alum shale or the sandstone, is not to be distinguished from 

 that of the proper coal seams. We find also, in examining the latter, 

 evident vestiges of trees or branches, betraying the vegetable origin of 

 this most useful mineral ; which is further confirmed, by our uniformly 

 observing vegetable impi'essions in the shale that covers the coal 

 seams. 



As the blocks of petrified wood in our strata, are generally 

 found lying flat, with their longest diameters in the plane of the 

 strata, a number of such blocks, in the coaly state, lying together. 



