A HISTORY OF BERKSHIRE 



northern portion is composed of grassy downs with softly curving out- 

 lines, or of the more undulating tracts which have been brought under 

 cultivation. Further south the chalk becomes covered with ' clay with 

 flints ' and ' brick-earth,' and is often a woodland tract, and extensive 

 heathlands prevail where the tertiaries are present, and boggy ground 

 where these are impervious. From the base of the porous chalk 

 copious streams of water issue, in which large quantities of water cress 

 are grown. 



READING BEDS. The lowest tertiary strata found in Berkshire 

 consist very largely of stiff clay, but also include beds of sharp sand and 

 loams. These beds once formed an unbroken sheet extending over 

 the whole of the chalk, but they have been largely swept away by 

 denudation, and beyond their main mass a very large number of outliers 

 testify that they had formerly a much wider range. 



They are now found scattered over a large area of southern Berk- 

 shire, and are shown on the geological map. The varied soils formed 

 by them necessarily give rise to a varied vegetation, which includes 

 several local species, but as the beds are much broken up it would not 

 be easy, even if desirable, to keep their flora apart from that of the 

 other members of the tertiary beds. The extensive deposit of drift 

 gravels with which they are often covered also increases the difficulty 

 of keeping the flora of the ' Reading Beds ' distinct. One must 

 content oneself by saying that where the * plastic clay ' is the pre- 

 dominating surface, there plants which prefer an argillaceous soil will 

 be found, so that the bladder sedge (Carex vesicaria) and the greater 

 spear-wort (Ranunculus Lingua) appear in ponds on the clay of the 

 ' bottom bed ' near Marlstone and Yattendon ; in Oare Woods the 

 pale sedge (Carex pallescens) is to be found. South of Newbury, in 

 ponds, the pennyroyal (Mentha Pulegiuni) occurs ; at the base of the 

 Wargrave outlier is a marshy spot which gives a home for the tussock 

 sedge (Carex pantcu/a fa), etc. On the sandy portions of the beds sand- 

 loving arenaceous plants are necessarily found, such as the cudweed 

 (Filago apiculata), the clovers Trifolium striatum and T. arvense, the 

 bird's-foot (Ornitbopus perpusillus), the hawkweeds Hieracium boreale^ 

 H. sciaphilum and H. umbellatum. The drift gravels which overlay 

 these Reading Beds give a specially interesting flora, as from the absence 

 of rich pasturage and the more exposed condition of the surface soils 

 such local species as the cinquefoil (Potentilla argentea), the clovers T. 

 scabrum, T. subterraneum, the pinks Dianthus Armeria and D. deltoides, 

 the centaury (Erythrcea ramosis sima] , and the scabious (Jasione montana) 

 are found, as well as a very varied bramble flora. 



THE LONDON CLAY is a thick mass of a bluish or greyish clay, 

 which weathers brown on the surface, and has a broad outcrop in Berk- 

 shire. The range of hills from Cold Ash Common to Mare's Ridges 

 consists very greatly of this formation. There are several outliers north 

 of the Kennet, such as the large area of Bucklebury Common, where 

 the clay is much obscured by drift gravels. South of the Kennet the 



46 



