STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 163 



layer near the bottom appears to contain grasses, stem fragments 

 and chips of wood. The basal coal is almost black as are also the 

 lenses or local layers of amorphous coal. When freshly mined, the 

 mass is distinctly woody, tough and somewhat elastic ; some large 

 pieces are brownish-yellow as if from a recent bog. Often the 

 " brown wood of a single piece verges into black, and even into a 

 typical glossy lignite, having a conchoidal fracture and approaching 

 jet. It is notable that the probable saturation with decomposition 

 products in solution, that has produced the jet-hke wood, resembling 

 black vulcanized rubber, has not penetrated to the center of some 

 of the fragments, which are inwardly brown or even yellow." Parts 

 of some fragments appear to be charred while other parts are brown 

 and woody. Wood makes great part of almost all the hard pieces 

 examined, and logs, lying in all directions, are frequently in masses. 

 To the naked eye, resin appears to be present in small quantity ; 

 silicified stems rarely occur. 



The noteworthy features of the bed at Wilton, as summarized by 

 White, are (i ) an underclay, seemingly penetrated by roots; (2) 

 evidence of periods, when herbaceous vegetation held the ground in 

 certain areas and produced thin benches; (3) evidence of periods of 

 great accumulation of wood of arboreal size; (4) relative scarcity 

 of thinly laminated earthy or amorphous lignite (peat), this being 

 dependent on the more or less nearly complete decay of the plant 

 tissues; (5) evidence of frequent near approach to asepticity in the 

 water body, so that decay seems to have been arrested quickly; (6) 

 evidence that the surface was exposed at times to air, leading to 

 formation of mineral charcoal. He thinks that the high water-con- 

 tent is a legacy from an unreduced or immature brown peat and also 

 that the accumulation of logs, decayed only in part, indicates rapid 

 growth of the coal. 



The coal at Glendive, Montana, is very near the bottom of the 

 Fort Union ; it has been followed in a northerly direction for more 

 than 50 miles. The fuel is dull black lignite, containing a large 

 proportion of wood, sometimes in great slabs, both dull and jetified. 

 No roots. were seen in the underclay; mineral charcoal is present in 

 a layer as well as in scattered pieces and the coal contains very many 



