104 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DcC. 20, 



pliurets, and the occurrence of carbonate of iron in connexion with 

 them, prove that, when they existed as soils, rain-water, and not sea- 

 water, percolated them. (5) The coal and the fossil forests present 

 many evidences of subaerial conditions. Most of the erect and 

 prostrate trees had become hollow shells of bark before they were 

 finally imbedded, and their wood had broken into cubical pieces of 

 mineral charcoal. Land-snails and galley-worms (Xylohius) crept 

 into them, and they became dens or traps for reptiles. Large quan- 

 tities of mineral charcoal occur on the surfaces of all the larger beds 

 of coal. None of these appearances could have been produced by 

 subaqueous action. (6) Though the roots of Sigillaria bear some 

 resemblance to the rhizomes of certain aquatic plants, yet structu- 

 rally they are absolutely identical with the roots of Cycads, which 

 the stems also resemble. Further, the SigiUarice grew on the same 

 soils which supported Conifers, Lepiclodendra, Cordaites, and Ferns, 

 plants which could not have grown in water. Again, with the ex- 

 ception, perhaps, of some Pinnularice and Aster o^hyllites, there is a 

 remarkable absence from the Coal-measures of any form of properly 

 aquatic vegetation. (7) The occurrence of marine or brackish- 

 water animals in the roofs of coal-beds, or even in the coal itself, 

 affords no evidence of subaqueous accumulation, since the same thing 

 occurs in the case of modern submarine forests. For these and 

 other reasons, some of which are more fully stated in the papers 

 already referred to, while I admit that the areas of coal-accumu- 

 lation were frequently submerged, I must maintain that the true 

 coal is a subaerial accumulation by vegetable growth on soils wet 

 and swampy, it is true, but not submerged. I would add the further 

 consideration, already urged elsewhere, that, in the case of the fossil 

 forests associated with the coal, the conditions of submergence and 

 silting-up which have preserved the trees as fossils must have been 

 precisely those which were fatal to their existence as living plants — 

 a fact sufficiently evident to us in the case of modern submarine 

 forests, but often overlooked by the framers of theories of the accu- 

 mulation of coal. 



It seems strange that the occasional inequalities of the floors of 

 the coal-beds, the sand or gravel ridges which traverse them, the 

 channels cut through the coal, the occurrence of patches of sand, 

 and the insertion of wedges of such material splitting the beds, have 

 been regarded by some able geologists as evidences of the aqueous 

 origin of coal. In truth, these appearances are of constant occur- 

 rence in modern swamps and marshes, more especially near their 

 margins, or where they are exposed to the effects of ocean-storms or 

 river-inundations. The lamination of the coal has also been 

 adduced as a proof of aqueous deposition; but the microscope shows, 

 as I have elsewhere pointed out, that this is entirely different from 

 aqueous lamination, and depends on the superposition of successive 

 generations of more or less decayed trunks of trees and beds of 

 leaves. The lamination in the truly aqueous cannels and carbo- 

 naceous shales is of a very different character. 



It is scarcely necessary to remark that in the above summary I 



