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memoir. The most important of these relate to the Knowlbury field, 

 which, from its juxta-position to the larger field of Coalbrook, the 

 author terms a parasitic basin, and shows that it contains five seams 

 of coal and some bands of ironstone. The strata around the verge 

 of this basin are highly inclined, the dip diminishing as it approaches 

 towards a common centre. Sections across this small basin exhibit 

 considerable faults, which always occur as upcasts towards the higher 

 sides of the hills, where the basaltic matter has found vent : coal, in- 

 cluded between two of these upcasts, is described as much thickened 

 and in the state of cannel coal. 



Many fossil plants of new species from the Knowlbury and Gut- 

 ter Works are described by Professor Lindley. Recent investiga- 

 tions of Mr. Lewis are mentioned, which prove the existence of a 

 central dyke or funnel of basalt, thereby confirming the opinion 

 formerly expressed by Mr. Bakewell j and a complete transverse 

 section of these hills shows, that some beds of coal have been car- 

 ried up on the top of the basalt, and that this rock has flowed late- 

 rally so as also to overlie the coal. Although these coal measures 

 rest, in the greater part of their circumference, on the old red 

 sandstone, the existence of an interpolated band of true mountain 

 limestone is pointed out, which from the thickness of a few feet near 

 Bennett's-end, extends to a maximum developement of about 60 

 feet beneath one part of the Cornbrook field, where it contains sub- 

 ordinate beds of fine oolite, marl of various colours, abundance of 

 characteristic organic remains, and is much contorted and dislo- 

 cated. 



At Orelton, near the north-eastern extremity of this range, and 

 thus connecting it with the more eastern coal-fields, is a tortuous 

 range of oolitic mountain limestone, which rests upon the old red 

 sandstone and, exhibiting some extraordinary fractures and dislo- 

 cations, passes beneath the unproductive or lower coal grits. 



3. Old red sandstone. — In the vast formation comprehended 

 under the term old red sandstone, the author includes all the red or 

 green marls, conglomerates, sandstones, limestones, or flagstones, 

 the youngest or highest beds of which pass immediately beneath the 

 mountain limestone or carboniferous strata, and the lowest overlie 

 and graduate into, the superior members of the grauwacke series. 

 The author gives a geographical sketch of the western side of 

 the great trough in which this formation is deposited in Shropshire, 

 Herefordshire, and Brecknockshire ; the prevailing strike of which 

 is shown to be from N.E. to S.W., and the usual inclination to be 

 to the S.E. The upper beds of the formation, near the Brown Gee, 

 and partially near the Titterstone Clee Hills, expose a thin band of 

 conglomerate; then follow, in descending order, red or green marls, 

 with two or more zones of impure limestone called cornstone. To 

 these succeed micaceous flagstones and thin-bedded building stones, 

 with other strata of marls and cornstone. Massive varieties of con- 

 cretionary limestone, termed ball-stones, range along the western 

 foot of the Brown Clee. They are sometimes from 18 to 20 feet 

 thick, and are very dissimilar in quality and in appearance from the 



