STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 156 



at one locality, two embedded trunks, i6 and 20 feet long, 18 and 

 20 inches thick. The shorter stem was silicified throughout but the 

 other was so at only one end, lignitized at the other; the conditions 

 merging imperceptibly. At one place he saw a silicified stump, of 

 which the interior had decayed before, silicification began. Herndon 

 observed that within Smith county the coal beds are lenticular ; the 

 coal is brown to black, earthy to hard and frecjuently contains resin. 

 Phillips and Worrall in 1913 estimated the brown coal area of Texas 

 at not less than 60,000 square miles. The coal in many mines is very 

 tender and the loss in screening even the freshly mined coal is very 

 serious. 



D. White-^'' studied two typical localities in the Texas field, 

 whence a lignite, not very wood-like, is obtained. The deposit near 

 Hoyt in Wood county appears to have been made in a bayou or 

 lagoon of irregular form, one half to three quarters of a mile wide, 

 and it thins toward the margins. The floor is buff sandy clay, trav- 

 ersed locally by large roots of land plants, clearly in place. The coal, 

 with maximum thickness of 9 feet, is dark brownish black, fairly 

 well bedded, mostly moderately xyloid but with many lenses of 

 brownish, more massive coal, with conchoidal fracture, waxy to 

 satiny look, and amorphous ; zones of well-laminated coal were seen. 

 These, darker than the main benches, show cuticles and small woody 

 particles, like much Palaeozoic coal. The lenses are more or less 

 canneloid. Amber is present in the upper part of the bed, which is 

 distinctly xyloid ; mineral charcoal is not abundant, but there is 

 an inch parting which consists of densely matted fragments of char- 

 coal. There were large trees, one log, partly silicified and somewhat 

 flattened, was more than 70 feet long. The roof varies ; at times it 

 is " dirty coal," at others it is a bony coal and occasionally it is a 

 carbonaceous clay, several feet thick. 



The deposit near Rockdale was laid down similarly in an estuary 

 or bayou, 10 miles long and one half to one mile wide. Two beds 

 are worked by many owners in this area. The floor of the upper 

 bed is gritty clay overlying sand and well-filled with roots, travers- 

 ing the old soil in all directions at angles to the bedding; some of 

 these are more than 3 inches thidk. The bottom bench of coal con- 



-19 D. White, " Origin of Coal," Bureau of Mines, Bull. 38, 1913, pp. 12-19. 



