148 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



from the Eocene of Montana and Dakota that he believes the general 

 conditions during accumulation were similar. Woody parts are 

 more compressed in the older coal, but the canals of wood fibers are 

 well shown and appear to be filled with resin. Resins form a large 

 part of the mass, while spores and pollen exines compose not more 

 than 5 to lo per cent. ; the " fundamental matrix " or binding ma- 

 terial is derived, as in lignite, from cellulosic substances ; all grada- 

 tions are present from fibers to a homogeneous mass. The fibers 

 are mostly xylum elements of plants, but whether of trees, shrubs or 

 herbs is not always determinable. 



8. The Floor of Coal Seams. — The floor may be clay, sandy or 

 clayey shale, sandstone or limestone. Occasionally the transition 

 from coal to floor seems to be abrupt, but in most cases there is a 

 faux-mur. Even where this seems to be wanting, the basal part of 

 the coal is, in most cases, higher in ash than that above ; frequently 

 the faux-mur is bone and occasionally it resembles the " coarse coal " 

 of the Carboniferous. Limestone floors have been reported only 

 from southwestern Utah, where they contain marine fossils. Bulg- 

 ing floors have been reported from many localities. They are due 

 in some instances to irregularity of the surface on which the coal 

 accumulated ; in the Boulder District, petty swales were numerous, 

 in which accumulation began and afterward crossed the low divides — 

 after the manner so familiar in recent peat deposits. But " rolls " 

 in the floor often mark the courses of streams crossing the swamp 

 in its earlier stages. 



American reports contain few references to the presence of roots 

 in the floor ; two notes have been given for the Trinidad-Raton area 

 and D. White recognized characteristic underclays with roots in the 

 Boulder District. But the scantiness of references in detailed 

 reports indicates merely that the reporter did not look for the roots ; 

 Lesquereux,^*^ long ago, asserted that most of the underclays are 

 full of roots or rootlets. He visited exposures in the Raton Moun- 

 tains, Canyon City, Golden, Marshall in Colorado and Black Buttes 

 in Wyoming; at most localities, he found the shale containing such 

 abundance of roots that these seemed to be a compact mass. 



'^^'' L. Lesquereux, " On Formation of the Lignite Beds of the Rocky 

 Mountains," Amer. Jouru. Sci., Vol VII., 1874, p. 30. 



