RED MARL AND SANDSTONE. 



165 



The beds of red marl and sandstone of this formation, occupy a 

 considerable part of the midland counties in England, extending from 

 the eastern side of Yorkshire into Devonshire, and on the west, with 

 some interruption, from Cumberland to Gloucestershire. The beds 

 or strata never attain any considerable elevation in England; they 

 cover or enclose rocks of other formations : in Leicestershire and 

 Warwickshire they surround rocks of sienite, granite, porphyry slate, 

 greenstone, and quartz. The granite and greenstone of the Malvern 

 Hills, are covered, on the southern side, by the same red marl and 

 sandstone. In Devonshire, several rocks of greenstone and amyg- 

 daloidal trap are also surrounded by it; and at Rouvray in France, on 

 the road to Dijon, I observed a low range of sienitic and granitic 

 rocks, rising from a similar red marl, which, like the English red 

 marl, was covered by blue lias with gryphites. It was formerly main- 

 taiiied by Mr. Farey, that the sienitic and granite rocks of Charn- 

 wood Forest and Malvern, were merely anomalous masses in the red 

 marl ; and though this opinion was deemed extravagant, and after- 

 wards abandoned by Farey himself, I am inclined to believe, that 

 there is a greater connection between these different formations, than 

 has hitherto been admitted. 



The red marl and sandstone of England, appear to me to have 

 been formed principally^by the disintegration of rocks of trap, green- 

 stone, sienite, and granular quartz : the iron in the decomposing trap 

 rocks, has probably given to this formation its red colour. I conceive 

 that the argillaceous marls have also been formed principally from 

 the trap rocks, and the siliceous sandstone from the granular quartz 

 rock. That rocks of sienite, trap, and quartz, were once extensively 

 spread over the districts now covered with red marl, might, I think, 

 be sufficiently ascertained, by tracing them through the red marl dis- 

 tricts, where they just peep above the surface, or they might be dis- 

 covered by sinking. The sienitic rocks of Charnwood Forest may 

 be distinctly traced into Warwickshire ; from thence to the Malvern 

 Hills the connection may be followed ; and from the Malvern Hills 

 to the trap rocks in Gloucestershire, Somersetshire, and Devonshire ; 

 but every where accompanied by the red marl, or near to it. The 

 quartz rock at the Lickey, near Bromsgrove, is not, as has hitherto 

 been believed, the only rock of the kind in the midland counties ; it 

 may be found near Atherstone in Warwickshire, and is, doubtless, as- 

 sociated with the greenstone rocks in that neighborhood, as members 

 of the Charnwood Forest range of hills. 



* In ihe village of Hartshill, near Atherstone, when the author was at school 

 there, the quartz rock M^as employed in mending the roads : it is granular without 

 cement, and breaks into sharp edged fragments : it has a light reddish colour. 

 When a handful of the fragments are taken from the roads, and thrown upon the 

 ground forcibly in the dark, they produce numerous scintillations like stars,— an 

 experiment which has often excited the surprise of the author and his schoolmates. 



