174 Sub-formation of the Chalk 



other earthworks of many periods from the Neolithic 

 onwards. It has been suggested^ that the original purpose 

 of many of these works was to shelter and defend the 

 flocks from the attacks of predatory animals such as 

 wolves, coming from the forests of the lower country. 

 Be that as it may, it seems unlikely that primitive man 

 was responsible for the disforestation of such great areas 

 of the chalk upland as are marked by traces of his exist- 

 ence, and the conclusion is therefore indicated that much 

 of this grassland is primitive, or at least has existed since 

 the conditions of climate resembled at all closely those at 

 present obtaining. There may well have been originally 

 more scrub than there is now. 



In addition to this possibly primeval grassland, 

 occupying much of the rolling summits of the downs, 

 there is much pasture on the slopes of the escarpments 

 and valleys, and this has probably taken the place of 

 beeohwood and ashwood destroyed by man. 



The chalk grassland is almost everywhere used for 

 sheep pasture, and where the grazing is 

 ''f^iT'i^'^^ heavy the herbage is eaten very close. 

 pasture. When rabbits are abundant the turf is even 



more closely nibbled, and scarcely a her- 

 baceous plant is able to rise more than an inch or so 

 above the surface of the soil (Plate XVIII b). In places 

 freer from this constant grazing and nibbling the vege- 

 tation is able to develop much more vigorously, and a 

 rich and varied flora occurs (Plate XX b). 



The turf is springy, being formed of a close mat of 

 wiry herbage, often easily separable from the substratum. 

 It is made up of a multitude of species, among which 

 Festuca ovina is typically, but by no means invariably, 

 dominant. Besides the grasses and less abundant sedges 

 there are many dicotyledonous species, and the association 



' By the Messrs Hubbard. 



