494 On the Agricultural Geology of England and Wales. 



tions are to be ascribed to the erratic tertiaries, for he says the 

 rock is covered to such a depth with diluvial matter, that for all 

 practical purposes it may be dismissed from consideration. The 

 same remark applies to that large area of the New Red Sand- 

 stone which extends from Lancaster to near Worcester, and up to 

 the edge of the Penine chain. The variations of soil shown on 

 the map which accompanies Holland's Report on Cheshire are 

 clearly to be ascribed to the erratic tertiaries — to the varying 

 amount of denudation to which they have been subject, the form 

 of the denuded surface, and the depth and composition of the 

 warp, or unconformable deposit, thrown down on it. They are 

 varied also by occasional masses of sandstone which protrude 

 through in Alderley Edge and Delamere Forest, and by valley 

 deposits at different heights along the lines of drainage, in which 

 the materials of the denuded erratic tertiaries have been recon- 

 structed. In parts of Nottinghamshire there appears to be more 

 connexion between the soil and the rock beneath. 



Coal Measures, — Mr. Charnock's* description and diagram of 

 the soils on the coal measures of Yorkshire are virtually a reference 

 of their formations to superficial deposits and contours. The soil 

 is described as strong, resting on the ordinary yellow clay, which 

 is the general subsoil of the coal districts. Where the sandstone 

 and shale lie near the surface they produce a dry, and in some 

 cases very productive soil. The clay with its strong soils usually 

 occupies the valleys, and the entire rise on the lower swells, but 

 on elevated places only extends a limited distance up the rise, 

 w^here the sandstone comes through and a friable soil commences, 

 " as though the aluminous particles had slipped or been washed 

 down from the steeper inclinations, and formed the clay subsoil of 

 the lower levels." As the contour becomes more marked the transi- 

 tions from the friable soils of the sandstones are more remarkably 

 noticeable. In the maps attached to the Reports on Durham 

 and Northumberlandf little relation can be traced, except in the 

 mountainous parts, between the districts of soils into which they 

 divide the country, and the colours of geological maps. Want of 

 space, however, prohibits details, and we pass on to the old red 

 sandstone. 



Old red sandstone. — In the great Avork of Sir R. Murchison, 

 ' The Silurian System,' will be found not only some valuable obser- 

 vations on the agricultural characters of the old red sandstone 

 and the Silurian strata of the adjoining region, but some import- 

 ant general views respecting the relative influence of the substrata 

 and the superficial deposits on the fertility or sterility of soils. 

 Of the old red he says that in the high mountainous regions. 



* Journal of the Royal Agricultural Society, vol. ix. p. 289. 

 t Ibid., vol. viii. p, 422. 



