464 On the Agricultural Geology of England and Wales. 



pebbles of crystalline and subcrystalline rocks have been found, 

 mixed with a great abundance of erratic fossils of the oolites. 



Erratic Gravel of the Midland Counties. — Returning now to 

 the tract bounded on the W, by the Welch mountains and the 

 Malverns, and on the E. by the Penine chain and the Cots wold 

 Hills, we find that granitic boulders extend as far southwards as 

 Bridgenorth, from which point they decrease in size and quantity, 

 till they pass off into coarse gravel, composed of the same ma- 

 terials, which dies off in the fine gravel and sand of the vale of 

 Gloucester. Marine shells have been found in this gravel at 

 various points, the most southern of which is about three miles 

 south of Worcester, 



Before the granitic fragments disappear, other detritus of 

 marked character comes in, by which we are enabled to trace 

 the direction of the drifted materials of the erratic deposit further 

 to the south.* The most remarkable of these are the pebbles 

 of the lower Lickey quartz rock. Fragments of this rock re- 

 duced to the state of rolled pebbles by the marine action of the 

 new red sandstone epoch had been consolidated into a con- 

 glomerate of that series, which forms the upper Lickey range. 

 This conglomerate having been subsequently broken up by the 

 operations of the erratic period, its rounded pebbles, mixed 

 with the angular and partially worn fragments of the local rocks, 

 form a gravel, which is spread, in enormous quantities, over the 

 midland counties, particularly about Cannock Chase, in Stafford- 

 shire, and Coleshill, E. of Birmingham. It has been collected 

 also in large masses along the plains subjacent to the great 

 oolite escarpment, N.E. of Shipston-on-Stour, in Warwickshire. 

 The other fragments with which the pebbles of the Lickey quartz 

 rock are associated consist of white quartz, flinty slate, gneiss, 

 porphyry, compact felspar, trap, sandstone of several kinds, lias, 

 chalk, and flint. The gneiss must have come from Scotland or 

 Norv/ay, the white quartz and the slaty and porphyritic pebbles 

 may have been derived either from the mountains of Wales or 

 from Charnwood Forest. 



In short, in the centre of England, W. of the oolitic escarp- 

 ment, we have the junction of aline of drift from the N.W. with 

 another from the N.E. The united drift having crossed the 

 Cotswokls through a gap or depression in the ridge, takes a S.E. 

 direction into the valley of the Thames as far as London. 



The most distinctive detritus of the midland counties, having 

 a north-eastern origin, consists of pebbles \ of the red chalk of 

 Yorkshire, Lincolnshire, and the N.W. angle of Norfolk at 

 Hunstanton, which does not occur in place further S. Frag- 



* Buckland, Geol. Trans., First Series, vol. v. p. 521. 



t Ibid. 



