AS CONTRASTED WITH EPPING FOREST. 34I 



residua of deposits formerly occupying a higher level than their 

 present situation, and let down by the valley-ward flow of the 

 clay on which they rest, a progress too molecular to be termed 

 landslip, and too deep-seated to come under the denomination of 

 soil-creep. Landslips consist in the descent of one or more 

 continuous masses, gliding down more or less regular internal 

 planes of disconnection, as distinct from outward falls of cliff or 

 escarpment. Soil-creep, on tlie other hand, is chiefly, though 

 not wholly, due to alternations of frost and thaw, whilst the 

 descent of sheets of gravel and sand, without disturbance of the 

 bedding-planes, by lateral flow of the subjacent clay under their 

 weight, is the result of simple saturation, which frost would 

 rather hinder than help. It is, however, doubttul if in this 

 country the influence of frost ever penetrates deep enough to 

 affect the process in question. 



Detailed study of the environment of the beech groves elicits 

 the general rule that patches of gravel, of but few feet in thick- 

 ness, and resting on so gentle a slope of clay as to be almost 

 continuously water-logged, constitute the favourite habitat of the 

 beech. Bagshot or Westleton pebble-beds, or Glacial (or more 

 recent ?) gravels, seem to be indiff'erently selected, the hydrological 

 conditions being the main factors in the great question, " To be, 

 or not to be," for Fagus sylvatica. 



The chemical elements present in the soil, or in the percolating 

 waters, may have a minor influence on the ultimate development 

 of the trees, a neutral or alkaline condition being indicated as 

 favourable, acidity as hostile. The Chalk supports many noble 

 beech-forests, and the ashes of the timber contain a large pre- 

 ponderance of lime over other bases, whilst sulphates and 

 chlorides occur only in very limited proportions. In Hainhault 

 there is a much less quantity of gravel, and the fine sand of the 

 Bagshot Beds, as mentioned in a previous note (p. 246), is more 

 or less charged with sulphuric acid from decomposing pyrites. 

 Probably these considerations are not the sole causes of the 

 difference between Epping and Hainhault in respect of beech- 

 trees, but in the complex relations which affect the existence of 

 every form of life some factors are of paramount, others of minor 

 or no importance in each case, and I venture to think that those 

 I have indicated are amongst the foremost for the subject of his 

 note. 



