WILLIAMS ON THE TRAP-EOCK OF BLEADEN HILL. 47 



extent of 3 feet 9 inches, where this part also is found to enter 

 the side of the quarry ; so that the whole length of this splendid 

 fossil, so far as it is yet traced, is upwards of 44 feet, and its 

 greatest breadth is not more than 20 inches. At this point it has 

 evidently been the most compressed, being here only about 4 

 inches in depth ; but from the second branch to within 3 or 4 feet 

 of the top, the tree maintains, in a remarkable manner, almost its 

 original proportions. It will at first sight appear extraordinary 

 that the breadth within 6 feet of the lower end should not exceed 

 12 inches ; this however, without doubt, arises from the greater 

 degree of carbonisation which is evident at this part, and indeed 

 marks of the original exterior may be traced upon the adjoining 

 stone to the extent of 19 inches. The substance of the tree, 

 though not silicified, is hard and fine-grained, differing entirely 

 in appearance from the rock which surrounds it, having become 

 more highly impregnated with iron, to which probably its present 

 state of preservation is to be attributed. It is evident that the 

 mineralising process must have commenced prior to any extensive 

 decay, for in all probability the structure has been well preserved. 

 Microscopic sections, which I have not yet been enabled to obtain, 

 will of course afford the best evidence as to its affinity with other 

 fossils, and with recent wood ; but I may observe that there is an 

 appearance of concentric rings, and, moreover, a large develop- 

 ment of pith, but differing probably from every other described 

 fossil stem. The bark, in general, has been converted into a thin 

 layer of bright coal, which becomes fractured, and in part sepa- 

 rates, on removing the overlying rock ; but no trace of leaf-scars 

 or punctures have yet been detected either upon the stem or its 

 branches ; the decorticated exterior, particularly of the latter, 

 which presents a smooth surface with broad irregular stria?, hav- 

 ing a waved and somewhat twisted appearance. These branches 

 show indications of cicatrices, as though other lesser ones had 

 formerly been attached to them ; and it may be remarked that 

 small branches exhibiting this peculiar exterior have repeat- 

 edly been met with in the South Staffordshire coal district. I may 

 mention, in conclusion, that I have obtained some excellent sec- 

 tions of the wood, which show that the structure is remarkably 

 perfect, and prove the tree to have been coniferous. 



5. On the Trap-rock of Bleadon-hill, in Somersetshire. By 

 the Rev. D. Williams, F. G. S. 



Since the author's last communication on this subject*, the com- 

 pletion of the Railway cutting through the western point of 

 Bleadon Hill has disclosed several new and remarkable facts ; and 

 these have so materially changed his views respecting the origin 



* Geological Transactions, 2d ser. vol. vi. p. 561. 



