244 UPPER GREEN SAND, WEALDEN, AND UPPER OOLITE K0CK3. 



series of greenish sandy strata. The 

 whole of these beds are in m£iny places 

 full of fossils. 



Extent. — The Green Sand forms a narrow border round the whole of the 

 northern and western edge of the chalk, except in Yorkshire, where it has not 

 as yet been anywhere discovered at the surface. It skirts also the southern 

 edge of the chalk in Surrey and Kent, and its eastern boundaiy in Hampshire, 

 where it attains a breadth of eight or ten miles. It forms likewise the southern 

 portion of the Isle of Wight. 



Soil. — The upper beds, which are the greenest and most chalky, form an 

 open fiiable soil, easily worked, and of the most productive character. It con- 

 sists in general of an exceedingly fine sand, mixed with more or less of clay 

 and calcareous matter (see analysis, p. 234), coloured by greenish grains. It is 

 rich and productive of every species of crop, and the peculiar richness of this 

 soil has been remarked not only in England but also in the United States of 

 North America. In some parts of Bedfordshire the soils of this formation form 

 the most productive garden lands in the kingdom. In other localities, again, 

 where tlie soil is formed from layers of black or of white silvery sand, it produ- 

 ces naturally nothing but heath. 



The impervious gault clay forms in Cambridge and Huntingdon " a tliin, 

 coid clay soil, which, when wet, becomes as sticky as glue, is most expensive 

 to cultivate as arable land, and naturally produces a poor, coarse pasture." 

 Much of this tract, though unenclosed, is yet generally in arable culture, under 

 two crops and a naked fallow — tlie enclosed parts are chiefly in pasture, and 

 yield a rich herbage. 



The lower green-sand presents itself over a comparatively small surface, 

 is in some localities (Sussex) laden with iron ochre, and is there naturally un- 

 productive. 



B. — Oolitic System. 



7°. Wealden. 950 ft. The upper part consists of a fresh- 



a Weald Clay, 300. water deposit of brown, blue, or fawn- 



d Hastings Sand, 400. coloured clay, often marly and almost 



c Purbeck lime-stone, 250. always close and impervious to water. 



Beneath this are the iron or ochrey 



Hastings sands, which again rest upon 



the Purbeck beds of alternate fresh- war 



ter lime-stones and marls. 



Extent. — The Wealden rocks appear at the sui-face only in Sussex and 



Kent, of which they form the entire central portion. 



Soil. — The soil formed from the Weald Clay is fine grained and unctuous — 

 often pale coloured, emd containing much fine grained siliceous sand. It forms a 

 paste which dries and hardens almost like a brick, so that the roots of plants 

 cannot penetrate it. From the expense of cultivating such land, much of it 

 is in wood (Tilgate Forest), and some is in poor wet pasture. On the whole 

 of this tract, therefore, there is much room for improvement. The Hastings 

 sands produce a poor brown sandy loam which naturally yields only heath and 

 brush-wood. Much of this soil is in pasture, but, under proper cultivation, it 

 yields good crops of all kinds. Where the ruins of the Purbeck mai-ls are in- 

 tenriixed with it, the soil is of a superior quality. 



8°. Upper Oolite. 600 ft. The upper part of this formation con- 



a Portland Beds, 100. sists of the oolite* limestones and cal- 



b Kimmeridge Clay, 500. careous sand-stones long worked at 



Portland— the lower of the blue slaty 



* So named because they consist of small fig'^'-shaped granules, like the roe of a fish. 



