INTRODUCTION XXXlll 



The Upper Green sand has at the base a band of hard calcareous free- 

 stone, above which come soft glauconitic sands. The ground occupied 

 by this formation rises in a steep terraced escarpment above the Gault 

 plain, which is most prominent at Kingstone Lisle, Charlton, Milton 

 Hill, Berwick Prior, and Adwell. The upper part of the Upper 

 Greensand is calcareous and contains occasionally phospbatic matter. 

 These constituents render its soil very fertile, and its fertility is 

 further increased by the supply of marly debris, which every shower 

 of rain washes down from the Chalk escarpment and spreads over its 

 surface. The flora is consequently much more varied than that of the 

 Gault. About twentj^ miles south of the main outcrop of the Upper 

 Gi'eensand a small outlier of it is found at the base of Riever Hill, near 

 Inkpen, w^here the Chalk hills rise from the synclinal trough on the 

 south side of the Kennet. This outlier, which, from its containing 

 the village of Shalbourn, may be called the Shalbourn outlier, is about 

 three and a half miles long, and at its broadest part rather more than 

 a mile wide, but only a narrow strip on the eastern and northern side 

 is in Berkshire, by far the larger portion being in Wiltshire. It owes 

 its occuri-ence to a continuance of the anticlinal curve of the Vale of 

 Pewsey, the Chalk having been removed by denudation. Another 

 outlier of the Greensand occurs a little to the east of this, but it is 

 wholly outside our bounds, being in Hampsliire, and forms that 

 beautiful portion of country on which Sidmonton is situated. The 

 richer and more fertile country afforded by this formation is plainly 

 visible from the Chalk hills of Walbury Camp and Gibbet Hill. The 

 area of the Upper Greensand also contains three outliers of the 

 Chalk, namely, the two historic hills known as the Dorchester, or 

 Wittenham Clumps, and Cholsey Hill. 



Among the more local or interesting plants found on the Upper 

 Greensand may be mentioned — Myosurus minirmis, Papaver hybrichon, 

 Fumaria densiflora, Cerastium arvense, Spiraea Filipendula, Cariim segetwn, 

 Caucalis nodosa, and OenanHie crocata in its most northernly situation in 

 the county. Cnicus eriophorus, Crepin biennis, C. taraxacifolia, Cynoglossum 

 officinale, Htjoscyamus, Verlascutn nigrum, Linaria Elatina, L. spuria, Salvia 

 Verbenaca, Lamimn hylridum, Polygonum Bistorta, Ophrys muscifera, Scolo- 

 pendrium, Zannichellia, and Allium vineale are also found. Poiamogeton 

 densum is rather frequent in the brooks issuing from the Chalk escarp- 

 ment. Bromus arvensis, B. interruptus, Camelina sativa, and Lepidium Draba 

 also occur. In some instances plants are found which are more closely 

 connected with the Chalk formation, for example, Linaria repens, 

 Iberis amara, Cleynaiis, and Bromus erectiis. 



Hops are cultivated on the Upper Grtensand near Didcot, and 

 there are extensive orchards of plums and other fruit in the same 

 neighbourhood. 



