636 STEVENSON— FORMATION OF COAL BEDS. [November 3, 



than 8 feet in circumference, all broken off close to the coal, while 

 the prostrate trunks lie across each other in every direction. These 

 trunks, 15 to 30 feet long, are invariably flattened to the thickness 

 of one or two inches, but the bark is distinct on both sides. The 

 bark is well preserved on the stumps, converted into bright coal, 

 while the interior or woody part is dead looking, wath dull luster 

 like cannel. The stumps seldom rise above the surface. In some 

 cases the diverging roots can be followed for nearly a yard, but they 

 cannot be traced into the underlying shale. In some cases, Cala- 

 mites are crowded between the trunks ; Lcpidodendron and Lepido- 

 strohi are abundant on the surface, while among them one finds occa- 

 sional remains of fishes. A noteworthy feature is that there are 

 three coal beds within a vertical space of 12 feet, each of which 

 shows on its surface the remains of an ancient forest — and the same 

 beds are exposed a mile away. Beckett says that the coal, when 

 "broken with the grain," shows faint impressions of Calaiuitcs and 

 reed-like plants. Ick recognizes that " the position of the trees in 

 each bed of coal seems almost to preclude all doubt of their having 

 grown and perished on the spot where their remains are now found, 

 and the roots are apparently fixed in the coal and shale, which was 

 the original humus in which they grew." 



Binney^*^^ described the great SigiUaria stump, discovered at 7 

 miles east from Manchester and now in the museum of Owens col- 

 lege. The stump is filled with dark-colored fireclay but the roots 

 with a different material. The dark fireclay floor was penetrated 

 to about 3 feet by the stem and roots, the latter being, in part, 

 directed upward. , 



De la Beche^''- remarks that actual observations of rooted stems 

 are comparatively few because exposures are few. He and W. E. 

 Logan saw many vertical stems in a sandstone at a Welsh colliery. 

 The directly underlying shale contained ferns and leaves of other 

 plants distributed " around in the same manner as leaves and other 

 parts of plants may be dispersed around stems of trees in muddy 



'" E. W. Binney, " Description of tlie Dirkenfield SigiUaria,'' Quart. 

 Journ. Geol. Soc, Vol. II., 1846, p. 390. 



""H. T. de la Beche, "The Geological Observer," Philadelphia, 1851, 

 pp. 482-485, 4Q7- 



234 



