98 Horner's Geological Address, 



identical with, and almost all the rest have a near affinity to 

 species found in the Glasgow and other coal-measures. 



The theory which refers the coal to trees and plants which 

 have grown on the spot where it now rests, is illustrated by 

 Mr Lyell by observations he made in Nova Scotia, on the 

 south shore of the Bay of Fundy, at a place called " The Jog- 

 gins." He states that there is a range of perpendicular cliffs 

 composed of regular coal-measures, inclined at an angle be- 

 tween 24 and 30 degrees, whose united thickness is between 

 four and five miles. About nineteen seams of coal occur in 

 the series, and they vary from two inches to four feet in 

 thickness. The beds are quite undisturbed, save that they have 

 been bodily moved from the horizontal position in which they 

 must have been deposited to that inclination they now have. 

 In these coal-beds, at more than ten distinct levels, are 

 stems of trees, in positions at right angles to the planes of 

 stratification, that is, which must have stood upright when 

 the coal-measures were horizontal. No part of the original 

 plant is preserved, except the bark, which forms a coating of 

 bituminous coal, the interior being a solid cylinder of sand 

 and clay, without traces of organic structure, as is usually 

 the case with Sigillaria, and like the upright trees in the 

 coal-measures cut through by the Bolton Railway. The 

 trees, or rather the remains of stems of trees broken off^ at 

 diff^erent heights above the root, vary in height from six to 

 twenty-five feet, and in diameter from fourteen inches to four 

 feet. There are no appearances of roots, but some of the 

 trees enlarge at the bottom. They rest upon, and appear to 

 have grown in, the mass which now constitutes the coal- 

 seams and under-lying shale, never intersecting a superior 

 layer of coal, and never terminating downwards out of the 

 coal or shale from which the stem rises. The underclay or 

 shale often contains Stigmariae. Here then, he states, are 

 the remains of more than ten forests, which grew the one 

 over the other, but at distant intervals, during which each, 

 from the lowest upwards, was successively covered by layers 

 of great thickness of clay and solid stone, the materials of 

 which must have been arranged and consolidated under the 

 surface of water, and the vegetation of every layer in which 

 the upright trees are fixed must have grown on land. 



