456 On the Agricultural Geology of England and Wales. 



Diluvium of the Oxford clay 

 Lias 



The upper chalk . . , 

 Some of the lower chalk 

 The shelly oolite . . 

 The great oolite . . . 



Magneslan limestone 

 Carboniferous limestone 



jCalcareous gravelly soils. 



Soil composed of calcareous fragments, 

 with little or no siliceous matter. 



\Calcareous fragments, with a consider- 

 j able portion of siliceous matter. 



Siliceous Soils. 



Silex the prevailing mineral, either as fine sand or gravel— clay the mineral 

 next in abundance — lirne sometimes present. 



Sand of the plastic clay . . 



Mihslone g-rit *.'!!!'.** l^^^J friable, dry, and loose sand, with 

 Old red sandstone ' \ ' ' ' '[ ^^^^^ aluminous, no calcareous matter. 

 Granite 



Diluvium of the plastic clay " . 



„ gault .... 

 new red . . . 



,, ,, coal measures. 



Gravelly, strong soils, with a considerable 

 portion of clay. 



The graywacke, or clay slate . ")c -i ^ e r + 



Some of the basalt . j^^^^^ composed of fragments. 



The alluvial 



The greensand 



The new red sandstone .... 

 The old red marls of Here- 

 fordshire 



Some of the basalt 



Calcareous matter, silex, and clay- 

 of the first quality. 



-soils 



This arrangement^ it will be observed, is a deviation from the 

 plan announced in the outset, of abjuring previous classifications 

 and adhering to local names, referring them to the geological 

 formations on which they rest. It is, to all intents and purposes, 

 a chemical classification of soils, and a reference of those of each 

 formation to one or other of the chemical divisions : and some 

 such double classification soils require — chemical as regards their 

 composition, geological as regards their relation to the different 

 rock formations, to the erratic tertiaries (diluvium) or the alluvial 

 deposits. 



The characters assigned to the soils may be considered as the 

 prevailing characters of the formation umen the rocks are exempt 

 from the influence of the surface deposits. They can only be 

 received under this limitation. The extent of each formation so 

 circumstanced is a question into which the author has scarcely 

 entered. There are variations moreover in the mineral character 

 of many of the rock formations, which are passed over with little 

 notice, and which, supposing soils to be w^iolly derived from the 



