52 PHYSICAL GEOGRAPHY. CHAP. 



or way ; while ' rhycP is really a ford a curious example of adopted 

 words with exchanged meanings. 



Waterfalls can hardly be said to occur in the whole of the Oxford 

 district ; a circumstance which might have been affirmed from 

 considering the nature of the chalk, oolite, sandstone, and clay 

 which compose the strata. For these are not so unequal in their 

 resistance to waste as to allow of much local undermining of clay 

 and much overprojecting of rock, the main causes of the frequent 

 waterfalls among palaeozoic strata. Rapids, however, alternating 

 with pools, favourable to the angler, occur often where the varying 

 beds of oolite cross the upper branches of the Thames, as on the 

 Churn, the Coin, and the Windrush ; and advantage is taken of 

 the more rapid descents of the stream for the establishment of 

 many water-mills. 



Forests, Heaths, Indigenous Plants. In many parts of England 

 large, open, unenclosed, and thinly-peopled districts, with no more 

 than the ordinary, or less than the ordinary clothing of trees, are 

 called ' forests,' as if exterior to or beyond (foris) the more settled 

 and cultivated country. Some of these may have been anciently 

 woody tracts, like the ' hursts ' of Sussex. In the district round 

 Oxford the great forests of Wychwood and Whittlebury are re- 

 markable examples of mixed sheep-downs and pleasing glades, 

 among extensive masses and irregular groups of really forest trees. 

 Much wood still grows on the Chilterns, and some of the great 

 parks of the Cotswold have been formed amidst or in close adhesion 

 to earlier forests, as Oakley, Bendcombe, Stowell, Charlbury, Wood- 

 stock. In other parts vast woods of native growth, and that ancient 

 occupant or immigrant the beech c , occupy the uncultivable steeps 

 of the hills, as about Birdlip and Stanway ; while Shotover and 

 Brill have lost their trees, and almost their title as forest hills. 

 Perhaps my attention has not been critical, but I do not remember 

 to have seen any considerable surface of heath in this whole 

 district. Calcareous soils, like those of the oolitic hills and the 

 chalk downs, are not suited to the growth of erica or calluna, nor 

 are the clay vales better adapted to them. Some tracts, as Churchill 



c The noble elm which fills the valleys of Wessex and Mercia, and penetrates 

 to Northumbria, can be traced back three centuries; the chestnut eight; no date 

 can be assigned for the arrival of the beech. These trees are not found in old alluvial 

 deposits, nor have they been employed in ancient boats or burials. 



