f'.— GEOLOGY. 57 



grow upon it without preparation. And Lomax remarks : ' In order to 

 prepare a humus for the higher plants humic material must have 

 accumulated by the growth of lower orders.' 



The general result of Lomax 's studies — in which result my experi- 

 ence enables me to concur — is that the base of a seam is a rather soft 

 coal, exhibiting upon a vertical face a dull ground mass with fine spindle- 

 shaped streaks of bright, lustrous coal, apparently composed of small 

 scraps of a variety of plants of what the modern gardener would term 

 the herbaceous type. Following this we have the appearance of a 

 bright coal with sections of compressed stems or branches of trees inter- 

 mingled with ' humic ' material and spores. In the upper part of the 

 seam in general hard coals often occur, consisting mainly, or even 

 exclusively, of megaspores and microspores, with an occasional 

 sporangium, or even a complete fruit. 



This is the simple succession. There may, however, be a recurrence 

 of any of these phases. At first inspection the sequence seems to fortify 

 Lomax 's 'inference that the giant Lycopods demanded a soil of 

 humic materials upon which to grow, but this inference must admit 

 of many exceptions to meet the innumerable cases of fossil-trees stand- 

 ing rooted in sandstone (gannister), or other purely mineral deposit, 

 with no trace of humic soil. I have also seen a two-inch seam with 

 its underclay resting upon a coralliferous limestone into which the 

 stigmarian roots had penetrated. 



The nature of the last crop on the ground is not infrequently indi- 

 cated by the plant-remains in the roof. In the coalfield nearest us the 

 most common occurrence is to find in the shales of the roof prostrate 

 stems of Sigillaria, very often in great numbers. Not infrequently the 

 mud-filled stumps forming the dreaded ' pot-holes ' stand in attitude of 

 growth in the roof shales; their roots, too, may sometimes be detected 

 ramifying in the seam or on its surface. The great Barnsley Bed is 

 sometimes in this condition, but occasionally the last crop of this seam 

 when overwhelmed and disowned in muddy water was a profuse growth 

 of the fern-like Pteridosperms, such as Neuropteris heterophyllus . At 

 South Kirkby colliery a whitish efflorescence from the shale with the 

 black carbonaceous plant-remains gives the aspect of a sheet out of 

 a botanist's Jiortus siccus. 



Cannel. 



I have already mentioned that, in all those characteristics which 

 prove the growth in place origin of true coal, cannel seams present the 

 exact reverse, so that here all authorities are agreed that drifting in 

 some form must be invoked, but there are other forms in which the 

 material occurs to which the general theory can be applied only with 

 some qualification. 



The structure and composition of cannel have an important bearing 

 upon all questions of its origin. It is sometimes described as consisting 

 of spores, but in fact all the more exact descriptions speak of a dense 

 amorphous ground mass in which the recognisable structures are usually 

 spores. My observations show that they constitute only a small fraction 

 of the whole. Other plant-remains are rare; indeed, I can recall very 

 few examples, of which the most notable was a calamitean stem of 



