INTRODUCTION 71 



the southern, eastern, and to some extent central 

 areas. 



Altitude in turn regulates the distribution of 

 aquatic vegetation and fenland, and these are found 

 in the lowland areas in central and eastern England, 

 where, in the last case, the larger rivers have their 

 chief outlets. 



Proximity to the sea regulates the distribution ot 

 maritime vegetation, and it is only around the coasts 

 and in inland salt regions such as Cheshire and 

 elsewhere that halophytes or salt-loving plants are 

 to be found. 



Primarily the intermediate types of plants that 

 require a moderate degree of moisture are distributed 

 over areas where the soil is not water-logged, or 

 again where the slope or character of the soil, sandy, 

 etc., does not make for dry-soil conditions. The 

 wet clay areas of the Midlands give rise to a moisture- 

 loving type of vegetation. The hilly areas, where 

 the soil is quickly or well drained, or sandy, and 

 where the rainfall is not heavy, are most favourable 

 to the growth of dry-soil types. 



The character of the soil determines the nature 

 of the plant formation in the case of land-plants. 

 The chemical and the physical characteristics are 

 both equally important in determining the particular 

 type of vegetation. There are a large number of 

 different geological formations (see Fig. 11) which 

 have broadly western and eastern distribution if we 

 divide the rock formations up into an older series or 



