ANNIVERSARY ADDRESS OF THE PRESIDENT. I7l 



has any theory been yet advanced with which it has been possible 

 to reconcile all the appearances which the coal-measures exhibit, all 

 the variety of forms in which coal is found. Indeed the more closely 

 we examine the phaenomena, the more do we feel the distance we 

 are from a satisfactory explanation of them. According to some 

 geologists, coal-seams and their accompanying strata are accumula- 

 tions of land plants and stony detritus carried down by rivers into 

 estuaries, and deposited in the sea, where the vegetable matter un- 

 dergoes changes that convert it into coal. Others are of opinion 

 that coal is the altered residuum of trees and smaller plants that 

 have grown on the spot where we now find them ; that the forests 

 were submerged and covered by detrital matter, which was upraised 

 to form a foundation and a soil for another forest, to be in its turn 

 submerged and converted into coal, and that thus the alternations 

 which the vertical section of a coal-field exhibits are to be accounted 

 for. 



In the works of the last year to which I have chiefly referred, 

 we find the former theory maintained by Sir R. Murchison as most- 

 generally applicable ; Mr. Lyell is more inclined to adopt the latter. 

 Sir R. Murchison dwells upon the facts of the alternations of coal 

 with limestones containing marine remains, which are so frequently 

 met with in most countries where coal-fields prevail ; and as a stri- 

 king instance of this, he refers to the Donetz coal-field which I have 

 already alluded to. A remarkable example of a similar kind, occur- 

 ring in Maryland, is mentioned by Mr. Lyell. At Frostburg a black 

 shale ten or twelve feet thick, full of marine shells, rests on a seam 

 of coal about three feet thick, and 300 feet below the principalseam 

 of coal in that place. The shells are referable to no less than seven- 

 teen species, and some of them are 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 Joggins." He states that there 

 is a range of perpendicular cliff's composed of regular coal-measures, 

 inclined at an angle between 24- and 30 degrees, whose united thick- 

 ne!«s 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 thick- 

 ness. 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 n coat- 

 ing of bituminous coal, the interior being a solid cylinder of sund 

 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 



