26 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 2, 



overlying shales bend downward into the tops of these stumps, show- 

 ing that the material within was more compressible than that without, 

 perhaps in consequence of some vegetable matter remaining at the base 

 of the trunk. The roots of the larger tree have Stigmaria-markings, 

 and the rootlets were distinctly preserved in the shale. Portions of 

 the surface of the trunk showed the markings of a broad-ribbed Si- 

 gillaria, with oval leaf-scars on the ligneous surface. The bark, which is 

 in a coaly state, is about an eighth of an inch in thickness, and its ori- 

 ginal strength and durability are well illustrated by the circumstances 

 in which these trunks have been preserved. The detailed Section, 

 p. 4, sufficiently illustrate the beds immediately succeeding, including 

 the main coal. The shale roof of the latter, however, merits special 

 remark. It abounds in large prostrate trunks of Sigillaria and 

 Lepidodendron. One of the former has been traced for 30 feet in 

 the roof of the mine. Poacites, Asterophyllites, Ferns, and other 

 leaves also abound in it, and many of these, as well as the trunks 

 of the prostrate trees, have attached Spirorbis. Shells of Modiola 

 also occur, though rarely. In addition to all this, there are erect 

 stumps, the Stigmaria-rootlets of which insinuate themselves like 

 worms within the bark of the fallen trunks buried in the same shale. 

 A collection from this bed gives a fine picture of the flora of these 

 swamps of the Coal period. 



On the surface of a bed of clay, 8 feet above the main coal, stands 



Fig. 5. — Section from the upper part o/ Group XXIII. (p. 4). 



1 . Shale and sandstone. Plants with Spirorbis attached ; Rain-marks ? 



2. Sandstone and shale : 8 feet. Erect Calamites. f An erect coniferous ? tree, rooted on 



3. Grey sandstone: 7 feet. i. the shale, passes up through 15 feet of 



4. Grey shale : 4 feet. (_ the sandstones and shale. 



5. Grey sandstone : 4 feet. 



6. Grey shale : 6 inches. Prostrate and erect trees, with rootlets ; leaves ; Modiola ; and Spi- 



rorbis on the plants. 



7. Main coal seam : 3 feet 6 inches. 



8. Underclav with rootlets. 



