512 Geological Society : Anniversary Address. 



COAL FORMATION. 



The Society has received from Professor Ansted a paper on the 

 Carboniferous and Transition Rocks of Bohemia, a country which 

 he visited last summer, directing especial attention to the district 

 between Prague, Luditz and Pilsen, which he has illustrated by sec- 

 tions made from personal observation. Above the fundamental 

 granite and gneiss he found extensive deposits of grauwacke, on 

 which lie, in unconformable superposition, disconnected patches of 

 the coal formation. The age of this coal is well known, from the 

 fossil Flora of Count Sternberg, who resided in the midst of it near 

 Swina, to be identical with that of the great Coal formation of En- 

 gland. Mr. Ansted gives information also as to the action of trap 

 rocks in producing disturbances of the strata in this district ; and re- 

 specting dislocations, by which the grauwacke is several times placed 

 on a level with the coal measures, whilst in some cases the strata are 

 inverted and the coal measures laid beneath the grauwacke. 



We have received an interesting communication from Mr. Hawk- 

 shaw respecting a remarkable disclosure made in the Bolton Railway, 

 six miles north of Manchester, of five fossil trees in a position vertical 

 to the plane of the strata in which they stand. The roots are im- 

 bedded in a soft argillaceous shale immediately under a thin bed 

 of coal. Near the base of one tree, and beneath the coal, more than 

 a bushel of hard clay nodules was found, each inclosing a cone of 

 Lepidostrobus variabilis. The bark of the trees was converted to 

 coal, from one quarter to three quarters of an inch thick ; the sub- 

 stance which has replaced the interior of the trees is shale ; the cir- 

 cumference of the largest of them is 15^ feet at the base, 7 at the 

 top, and its height 11 feet. One tree has spreading roots, four feet 

 in circumference, solid and strong. By the care of Mr. Hawkshaw 

 these trees have been preserved, and a covering is erected over 

 them. The attendant phaenomena seem to show that they grew 

 upon the strata that lie immediately beneath their roots*. 



Mr. Barber Beaumont, in a communication respecting these same 

 trees, considers that no drifted plants occur in coal fields, and that 

 all the vegetables which are now converted into coal, grew upon 

 swampy islands covered with luxuriant vegetation, which accu- 

 mulated in the manner of peat bogs; that these islands, having 

 sunk beneath the sea, were there covered with sand, clay and shells, 

 till they again became dry land, and that this operation was repeated 

 in the formation of each bed of coal. In denying altogether the pre- 

 sence of drifted plants, the opinion of the author seems erroneous ; 

 universal negative propositions are in all cases dangerous, and more 

 especially so in geology : that some of the trees which are found erect 

 in the coal formation have not been drifted, is, I think, esta- 

 blished on sufficient evidence ; but there is equal evidence to show 

 that other trees, and leaves innumerable which pervade the strata 

 that alternate with the coal, have been removed by water to con 



[* See the abstract of this paper in L. & E. Phil. Mag. vol. xv. p. 539, 

 and also that of a further communication from Mr. Hawkshaw, in the 

 present number. EDIT.] 



