52 The Soils of Engla/nd and Wales 



with ash wood on the limestone exposures, were the 



natural types of vegetation. 



The Oolites, which follow the Lias, also run from the 



coast of Dorset to the coast of Yorkshire. 



Oolites. T 1 1 J! 



Their outcrop occupies a broader band oi 



country than the Lias, the greatest breadth being in 



the east midlands, where however the eastern division is 



overlaid by the alluvium and peat of the Fen District. 



The Oolites are partly composed of comparatively hard 

 rock forming hill-ranges, the most important of which, 

 the Gotswold Hills in Gloucestershire, and the Cleveland 

 Hills of north-east Yorkshire, attain a height of over 

 1000 feet (305 m.). The Oolite hills of the south, 

 notably the Cotswolds, are very pure limestones, but as 

 the outcrop is traced northwards the limestones partly 

 give place to rocks of a different lithological character, 

 while the north-east Yorkshire representatives of the series 

 are mainly non-calcareous. 



The vegetation of these last has been studied by 

 W. Gr. Smith, whose results are not yet published, but 

 it may be stated in a general way that the valley sides 

 of the Cleveland district are clothed with ash-oak woods 

 (indicating the outcrops of limestone) and with oak woods, 

 while the plateaux of the summits bear extensive heaths. 

 The limestones of the Cotswolds carry beechwood and cal- 

 careous pasture. The agricultural value of theOoUtes varies 

 very much according to the very variable local character 

 of the rock. In the stratigraphically upper portion of the 

 Oolite series are extensive belts of clay (Oxford clay and 

 Kimeridge clay) which are very heavy soils, expensive to 

 work, and are largely under permanent pasture. 



The Oolites are followed by the Cretaceous series, 



which occupies a broad belt of country ex- 



. tending from the Dorsetshire to the Norfolk 



coast, and bending north-westwards, appears 



again in Lincolnshire and south-east Yorkshire. 



