3i 8 SOIL TYPES [chap. 



intolerant ; a lime-hating plant like gorse, for example, 

 will grow freely enough on a calcareous soil in a garden 

 where it is protected from competition. But in nature 

 all plants are subjected to severe competition, and a very 

 small depression of their vitality brought about by the 

 presence or absence of some constituent of the soil, may 

 so turn the scale against them that they are almost 

 invariably crowded off areas of such soil, the exceptions 

 being due to some other favourable factor coming into 

 play locally. 



Sands. 



The typical sandy soils of this country are either 

 alluvial flats in the lower levels of our rivers, passing 

 into dunes where the sand accumulates near the sea, 

 or are directly derived from some of the many coarse- 

 grained sandy formations developed in England. The 

 Bagshot beds and the Lower Greensand form wide 

 areas in the south-east ; the sandy beds of the Oolite 

 produce similar soils in Northamptonshire and the 

 East Midlands ; further west and northward the Bunter 

 beds give rise to other very coarse-textured soils, as 

 does the Millstone Grit in more elevated areas in 'the 

 North. 



As these coarse-grained sands have been laid down 

 in rough water, they consist in the main of silica, which 

 alone is able to resist the degree of weathering and 

 attrition to which the original material has been 

 subjected. In consequence, the rock is initially with- 

 out much calcium carbonate or other material which 

 will yield soluble salts on further weathering ; the open 

 texture of the material also results in a very free 

 movement of soil water, and this continues the removal 

 of anything soluble. Occasionally a sandy rock is 

 found which has been largely formed by the disin- 



