ISO THE LAPSE OF TIME. 



The same tale is told by tlie coal-measures. Dr. 

 Dawson, of Montreal, has drawn out the argument from 

 the carboniferous formation 1 with extraordinary force 

 and a convincing plainness that leaves nothing to be 

 desired, for the benefit of any one who will read his 

 great work on Acadian geology. The formation of coal 

 depends on sub-aerial growths, affected by sub-aqueous 

 action. The trees and plants, out of which coal is 

 formed, for the most part could not possibly have grown 

 under water. The mud, the sand, the stone which 

 cover seams of coal, could not have been laid over them 

 without the agency of water to bring them down, and 

 spread them out in regular layers of stratification. 

 When the hollow bark of a tall tree is found erect upon 

 its roots, with those roots still permeating the clay from 

 which they once drew nourishment, it is evident that 

 time must be allowed for the growth of the tree, for the 

 almost complete decay which left nothing of it but its 

 bark and roots, and for the slow accumulation of sedi- 

 ment which has encased without overthrowing it. A 

 complete alteration must have taken place in the con- 

 ditions of the ground in the interval between the time 

 when the tree began to grow, and the time when a 

 length of seven or eight feet of its upright stem was 

 buried in mud. Layers, indeed, of sand and mud may 

 be spread out over small areas by storms and inunda- 

 tions with comparative speed ; but if above the sands 

 we come to thicknesses of limestone composed almost 



1 A formation later than the Devonian, and earlier than the New 

 Ked Sandstone. 



