28 Soils 



with drift materials. The soils are generally brownish grey, marly, 

 medium to heavy, loams lying on yellowish grey marly subsoils, often 

 with yellow or orange mottling due to high water tables. Coprolites are 

 plentiful in the surface soil,'' especially in those parts of the outcrop 

 bordering that of the Gault. 



The Gault soils are dark brownish grey in colour, and form the heaviest 

 of the clay soils. They lie on a buff-coloured clay subsoil, which merges 

 into blue-grey clay with orange mottlings. The formation is impermeable, 

 as are the soils wliich lie on its surface, except in so far as they are opened 

 up by tillage or by admixture with sand and gravel from neighbouring 

 formations. Consequently, the land tends to lie wet or water-logged in its 

 natural condition, except during dry seasons. The soils, however, have the 

 advantage of being calcareous (2 to 10 per cent of calcium carbonate, 

 increasing to 30 per cent or more within 3 ft. of the surface). This calcium 

 carbonate is not present as lumps or pebbles, but is finely disseminated 

 through the soil and so assists the formation of good tilths. 



There is not a very big outcrop o£ Lower Greensand but it is important, 

 being associated with intensive market gardening in the western part of the 

 County, and with fruit and flower culture in the centre of the County. 

 The soils are rich brown, loamy sands in the west, with more mellow 

 sandy loams to the centre. The parent material is a coarse quartz sand, 

 highly permeable, so that the chief features of the soils are their coarse 

 open character, very free drainage, low content of organic matter and 

 bases, frequently acidic reaction with signs of leaching and the formation 

 of iron-pan in the subsoils. This pan in some cases, and the proximity of 

 underlying clay in others, gives rise to localised patches where drainage 

 is impeded and the subsoil is mottled. 



The Kimeridge Clay gives rise to dark grey-brown clays and heavy 

 loams, often with a poor reserve of lime. They occupy low-lying flat 

 areas, and their chief handicaps are their poor tilth potentialities due partly 

 to difficulties of draining and partly to their low content of calcium 

 carbonate. 



The incidence of thin washes of drift materials gives to the other 

 Jurassic clay soils (Oxford Clay and AmpthtU Clay) a character of their 

 own. The surface textures are varied and there are wide variations in the 

 soil profile. They are all on the heavy side, but the top soil is frequently 

 much lighter than the subsoil. Their poor reserve of calcium carbonate, 

 however, is a factor against the easy production of good tilths. Low 

 lying and adjacent to the Fenland, their lack of fall and lack of internal 

 structure make them difficult to drain. 



' See p. 13 above, and p. 126 below. 



