Ch. XXIY.] COAL — ERECT FOSSIL TREES. 373 



most rapidly in low and flat tracks, in which there is a deep rich soil 

 and excessive moisture, supporting tall forest-trees and large palms, below 

 which bamboos, canes, and minor palms flourish luxuriantly. Such tracts, 

 from their lowness, would be most easily submerged, and their dense vege- 

 tation might then give rise to a seam of coal.* 



In a deep valley near Capel-Coelbren, branching from the higher 

 part of the Swansea valley, four stems of upright Sigillarim were seen, 

 in 1838, piercing through the coal-measures of S. Wales; one of them 

 was 2 feet in diameter, and one 13 feet and a half high, and they were 

 all found to terminate downwards in a bed of coal. " They appear," 

 says Sir H. De la Beche, " to have constituted a portion of a subterranean 

 forest at the epoch when the lower carboniferous strata were formed."f 



In a colliery near Newcastle, say the authors of the Fossil Flora, a 

 great number of Sigillarioe were placed in the rock as if they had re- 

 tained the position in which they grew. Not less than thirty, some of 

 them 4 or 5 feet in diameter, were visible within an area of 50 yards 

 square, the interior being sandstone, and the bark having been converted 

 into coal. The roots of one individual were found imbedded in shale ; 

 and the trunk, after maintaining a perpendicular course and circular form 

 for the height of about 10 feet, was then bent over so as to become hor- 

 izontal. Here it was distended laterally, and flattened so as to be only 

 one inch thick, the flutings being comparatively distinct.^ Such vertical 

 stems are familiar to our miners, under the name of coal-pipes. One of 

 them, *72 feet in length, was discovered, in 1829, near Gosforth, about 

 five miles from Newcastle, in coal-grit, the strata of which it penetrated. 

 The exterior of the trunk was marked at intervals with knots, indicating 

 the points at which branches had shot off. The wood of the interior 

 had been converted into carbonate of lime ; and its structure was beau- 

 tifully shown by cutting transverse slices, so thin as to be transparent. 

 (See p. 40.) 



These " coal-pipes" are much dreaded by our miners, for almost every 

 year in the Bristol, Newcastle, and other coal-fields, they are the cause 

 of fatal accidents. Each cylindrical cast of a tree, formed of solid sand- 

 stone, and increasing gradually in size towards the base, and being with- 

 out branches, has its whole weight thrown downwards, and receives no 

 support from the coating of friable coal which has replaced the bark. 

 As soon, therefore, as the cohesion of this external layer is overcome, the 

 heavy column falls suddenly in a perpendicular or oblique direction from 

 the roof of the gallery whence coal has been extracted, wounding or kill- 

 ing the workman who stands below. It is strange to reflect how many 

 thousands of these trees fell originally in their native forests in obe- 

 dience to the law of gravity ; and how the few which continued to stand 

 erect, obeying, after myriads of ages, the same force, are cast down to 

 immolate their human victims. 



* Hawkshaw, Geol Trans., Second Series, vol. vi. pp. 173, 177, pi. 17. 

 f Geol. Report on Cornwall, Devon, and Somerset, p. 143. 

 j Lindley and Hutton, Foss. Flo. part 6, p. 150. 



