166 



FORMATIONS OF NEW RED SANDSTONE. 



I was informed by T. Johnston, Esq. of Exeter, that he had fre- 

 quently exannined the red ground in the vicinity of the different trap 

 rocks in Devonshire, and that he invariably found it composed of 

 fragments of these rocks, increasing in size as he approached nearer 

 to them. The sand rock on which Nottingham and Nottingham 

 Castle are built, has, evidently, been formed of the ruins of more an- 

 cient rocks in its vicinity ; and the rounded pebbles of quartz and of 

 Lydian stone, granite, porphyry, jasper, and mica-slate, indicate that 

 they have come from rocks, formerly connected with the Charnwood 

 Forest range. Still nearer the Charnwood hills, the finest sandstone 

 contains fragments of slate, and the lower conglomerate is almost en- 

 tirely composed of the fragments of the Charnwood rocks, as before 

 observed. In the Vosges, the red sandstone every where accompa- 

 nies the granitic and transition rocks, of which also it contains frag- 

 ments. It must be recollected that the rocks most disposed to de- 

 compose or disintegrate, would be the soonest worn down. With the 

 exception of the Malvern range we have no rocks of soft granite, or 

 sienite in England, like those of Auvergne, or of the Forez moun- 

 tains in France ; and the reason why we have not, may be, that, from 

 their smaller magnitude, they were probably carried away by those 

 mighty inundations, that have swept over our present islands and 

 continents. The Malvern Hills, the Lickey, the Charnwood Forest 

 Hills, and the trap rocks in Gloucestershire, Somersetshire, and De- 

 vonshire, are the remaining nuclei of much larger ranges, as the scat- 

 tered fragments in the adjacent, as well as in distant districts attest. 

 If the red marl and sandstone in England, and in other countries, 

 were formed of decomposing rocks of trap, granular quartz, por- 

 phyry, sienite, and granite, the frequent occurrence of porphyroidal 

 beds in this formation may admit of a probable explanation. 



It is not intended to maintain, that every bed or stratum in this ex- 

 tensive formation is composed principally of the fragments of transi-,. 

 tion and trap rocks ; but it may be safely affirmed, that there are few 

 strata, in which some of these fragments may not be discovered. 



The red marl produces some of the most fertile soils in England, 

 which may be owing partly to its formation from soft trap rocks. 

 Some basaltic rocks decompose rapidly, and are known to form soil 

 favourable to vegetation ; several basaltic rocks in Staffordshire de- 

 compose into a reddish brown clay, moderately tenacious. 



A very remarkable discovery has been recently made (1828), of 

 the foot-marks of some unknown quadruped in strata of new red 

 sandstone, at the Corn Cockle Muir, three miles from Lochmaben in 

 Dumfries-shire. They were found forty-five feet under the present 

 surface ; the strata are inclined thirty-seven degrees. This circum- 

 stance was communicated to the author by Mr. Murray, jun. of Al- 

 bemarle Street, who showed him at the same time a plaster cast, ta- 

 ken from a slab of stone, in which the impressions were tolerably 

 distinct, and also part of a thin stratum of the stone itself, with indis- 



