116 



COAL PLANTS IN THE KNOWLBURY BASIN. 



having served as the nucleus round which the ferruginous matter has been concreted. 

 Among these plants Professor Lindley has determined the following : 



Catamites arenaceus? Ad. Brongn. Hist. Veg. Foss. 

 pi. 23. fig. 1. 



— cannceformis . F. F. pi. 79. 



cistii? Ad. Brongn. pi. 20. 



Lepidodendron tetragonum. Schloth. 

 Neuropteris flexuosa ? Ad. Brongn. pi. 65. 



Loshii. F. F. pi. 49. 



Odontopteris obtusa. F. F. pi. 40. 

 Otopteris dubia. F. F. pi. 150. 



Pecopteris lonchitica. F. F. pi. 153. 

 Sigillaria Murchisoni. F. F. pi. 149. 



. Two unpublished species, one of which I 



venture to name S. Lewisii. 

 Sphenopteris caudata. F. F. pi. 138. 



crenata. F. F. pi. 100. and 101. 



furcata? F. F. pi. 181. 



polyphylla. F. F. pi. 147. 



Stigmaria ficoides . F. F. pi. 31. to 36. 



The greater number of the fossil plants occur abundantly in other coal-fields, (see 

 p. 85,) but the remarkable species of Sphenopteris, S. polyphylla, together with the 

 Otopteris dubia and Sigillaria Murchisoni, have been figured, and so named by Lindley 

 and Hutton, in the Fossil Flora, from specimens collected by Mr. Lewis, in the Knowl- 

 bury basin, and forwarded by me to the Geological Society. It does not appear that 

 either the ironstone or shale contains any of the shells which are so abundant at Madeley 

 and other parts of the Coalbrook Dale field. 



The Knowlbury coal-field (see PL 30. fig. 7.) is traversed by two principal and several 

 minor faults, the prevailing direction of which is from north-east to south-west ; and a 

 transverse section, therefore, drawn from Tanner's meadow on the south-east, to the 

 Wint hills on the north-west, passes through these faults, to undersand the relations of 

 which, see PL 30. fig. 7. 



The first fault (a.) offers a marked exception to a prevailing law of faults, first I be- 

 lieve pointed out by Professor Phillips. As the side of this fault sloped away from 

 the place where the coal was lost without underlying, Mr. Lewis, according to the rule 

 alluded to, expected, in sinking downwards, to meet with the coal on the slope, i. e. on 

 what he considered the downcast side ; but being foiled in his endeavours, he drove up- 

 wards, when, to his great surprise, the coal was regained, above its former level, dipping 

 gently towards the centre of the basin. (See PL 30. fig. 7.) 



There are some remarkable and sudden changes, both in the thickness and compo- 

 sition of the coal seams, which are worthy of notice, as connected with these faults. 

 Between the first and second small faults (a and b), the coal seams and all the other 

 measures are much thickened, and in parts, doubled, for the space of nine yards. Be- 

 tween the second small fault (b), and the " Folly fault" (c), the Smith coal is also fre- 

 quently double its usual thickness. Again, the great coal having an average thickness of 

 about six feet and a half, is abruptly increased to* nine and ten feet, in the deep trough 

 included between the Folly fault (c) , and the Cannel coal fault (d) . In the rise from the 

 side of the Cannel coal fault to the High fault (e), the great coal again expands, and has 

 a thickness of ten feet ; but at the upper extremity of the high fault, it is again suddenly 



