1844.] 



291 



Section of the fault and tovbil tiees m 

 the ParUfield Colliery. 



large trees. A reference to the an- 

 nexed section will show the position 

 of these beds. The upper growth 

 of vegetation is on a stratum of coal 

 10 inches thick, under which is a 

 band of clay 2 inches thick ; this 

 lies undisturbed on the south end 

 of the platform, but is removed from 

 a few yards south of the centre to 

 the northern extremity ; and the second bed is there exposed, 

 covered, like the upper, with trunks, &c. The coal is here about 

 2 feet thick, and rests on a band consisting of 4 inches of shale and 

 8 of fire-clay. Five feet below this grew the third forest ; the 

 surface, where the upper beds have been removed, exhibiting 

 similar large stumps of trees, Lepidodendra, Catamites, &c. 



At Millfields colliery, one mile to the east, the same beds are 

 found at a depth of 126 yards. 



In several points of view, the deposit at Parkfield must be inte- 

 resting to geologists. The position of the trees, in each bed of 

 coal, seems almost to preclude all doubt of their having grown and 

 perished on the spot where their remains are now found, and the 

 roots are apparently fixed in the coal and shale, which was the 

 original humus in which they grew. 



As is generally the case with stems found prostrate in coal, these 

 stems are flattened. The woody tissue perished before the super- 

 incumbent strata were deposited, leaving nothing but a tube of 

 bark, which readily yielded to pressure. This is well seen in a 

 specimen, in which the bark is preserved, as well on the under as 

 on the upper side, while no woody tissue lies between ; the liber, 

 or inner side of the bark, from each side of the stem being crushed 

 into contact. It is from this cause that the ligneous structure of 

 coal fossils is so rarely preserved. The large trunks, in nearly all 

 cases, have been reduced to mere cylinders of bark, probably by a 

 process similar to that pointed out by Mr. Hawkshaw, and now to 

 be seen in tropical forests, where, by a combination of causes, a 

 large tree is reduced, in a few months, to a hollow tube which 

 yields to the slightest pressure. In this state, if a stem fMl, it is 

 flattened ; if it remain erect, the interior becomes filled up with 

 the ferruginous or carbonaceous materials of the surrounding bed, 

 which occupy the place of the rings of woody tissue. 



Whatever may be our success in discovering the botanical cha- 

 racter of these trees by microscopic aid, the evidence is not slight 

 that they were most of them allied to Conifer^e ; and few who have 

 carefully compared the Lepidodendra with the leaf-bearing stems 

 of the yew, spruce-fir, or various species of pine, can have much 

 doubt of the fossil plants being allied to these recent ones. 



In conclusion, I may observe that I have been induced to make 

 this communication to the Geological Society, because it is one of 

 the very rare instances of the surface of a bed of coal being ex- 

 posed over a large area. It is very probable that similar interest- 



