148 Sub-formation of the Older Limestones 



It is probable that at some past time, the whole of 

 the limestone areas of England below about 1000 feet 

 (c. 300 m.), or perhaps even 1250 feet (c. 380 m.), were 

 covered by a primaeval ash forest, just as similar places 

 on the older siliceous hills were once covered by forests of 

 oak {Quercus sessilifiora) and birch (Betula tomentosa). 

 The numerous place-names including the word "ash" 

 indicate that the abundance of Fraxinus excelsior is of 

 long standing. In north Derbyshire, for example, there 

 are Ashwood dale, Ashford, Money Ash (= " many ash "), 

 and, on the edge of the plateau at the upper limit of 

 woodland. One Ash. 



On the Chalk of the south and east of England, the 

 ash is a very abundant and characteristic plant, though 

 its dominance in woods is apparently confined to the 

 south-western region of the chalk outcrop. 



In the limestone districts above indicated, the ash 

 (Fraxinus excelsior) is the dominant tree of 

 ation to ^YiQ natural and semi-natural woods, whether 

 to lime. the soil be damp or dry \ In non-calcareous 



areas, the ash only becomes dominant or 

 abundant where the soil is wet or decidedly damp; and 

 it seems clear that, in any given natural station, the 

 abundance of the ash is due to one of two causes, either 

 to a high lime-content of the soil or to a high water- 

 content. Some of the local foresters are of opinion that 

 the timber of the ash grown on the limestone soils is 

 harder and more durable than that grown on the wet, 

 non-calcareous soils. 



The two most frequent woody associates of the ash are 



the wych elm ( JJlmus glabra Huds. = U. 



Associated montaim) and the hawthorn (Gratsequs 



tT*fiPH ^ Till ^ C/ 



shrubs. monogyna), both of which are more abun- 



dant in the ashwoods than in typical oak 



' These ashwoods cannot be separated from oakwoods on the basis of 

 a difference in the water-content of the soil, for in each case there is a 

 range from very wet to very dry soils. 



