112 Vegetation of the First Period of an Ancient World. 



have resisted any revolutionary Influence. Below the high main 

 seam (which, according to Mr. Forster's section of the strata is one 

 hundred and fifty yards helow the surface,) In a sand-stone, there 

 are numbers of fossil plants standing erect, with their roots In a small 

 seam of coal lying helow. These stems, as you will perceive by 

 the following diagram, are truncated, and lost in this seam, leaving 

 room to believe they may have formed part of this combustible 

 mass or bed. 



HIGH MAIN SEAM, 



10 inches. 



Again, in some of the seams, when the coal is worked away by the 

 miners, the roof often falls. Tliis is, to a considerable degree, ow- 

 ing to the number of vegetable impressions breaking the coherence 

 of the stratum, and bringing these fossils along witli it. It must be 

 observed, that in almost every instance they are surrounded by a 

 coating of very fine coal of about one-half or three-fourths of an inch 

 thick, having a polished surface with very little attachment to the 



This I doubt not is the cause of the fall ; the 

 fossil dropping out sometimes as much as three feet in length, leav- 



Often it falls in 



these large pieces, but sometimes the nature of the shale, of which 

 its substance is composed, causes It to fall in portions of different 

 thickness. It is to these falling pieces that the miner s expressive 

 term (kettle bottoms) applies. 



surrounding matter. 



ing a hole in the roof almost perfectly circular. 



These fossil plants run from two to eight feet in circumference. 

 The occurrence of numerous impressions which you may observe in 

 the specimens of parts of different plants in the shale, forming tlie 

 substance of these fossils, is to me, I must confess, very difficult of 



