CHAPTER IX. 



THE GROWTH OF COAL. 



MY early boyhood was spent on the Coal formation rocks 

 and in the vicinity of collieries ; and among my first 

 natural history collections, in a childish museum of many 

 kinds of objects, were some impressions of fern leaves from the 

 shales of the coal series. It came to pass in this way that the 

 Carboniferous rocks were those which I first studied as an 

 embryo geologist, and much of my later work has consisted in 

 collecting and determining the plants of that ancient period, and 

 in studying microscopic sections of coals and fossil woods ac- 

 companying them. For this reason, and because I have pub- 

 lished so much on this subject, my first decision was to leave 

 it out of these Salient Points: but on second thoughts it 

 seemed that this might be regarded as a dereliction of duty ; 

 more especially as some of the conclusions supposed to be the 

 best established on this subject have recently been called in 

 question. 



Had I been writing a few years ago, I might have referred to 

 the mode of formation of coal as one of the things most surely 

 settled and understood. The labours of many eminent geolo- 

 gists, microscopists and chemists in the old and the new worlds 

 had shown that coal nearly always rests upon old soil-surfaces 

 penetrated with roots, and that coal beds have in their roofs 

 erect trees, the remains of the last forests that grew upon them. 

 Logan and the writer have illustrated this in the case of the 

 series of more than eighty successive coal beds exposed at the 



