Xlii FLORA OF BERKSHIRE 



In the cultivated fields have been found Sllene anglica, FUmjo 

 apicukifa. Myosurus, Arnoseris, Anchusa officinalis, Mercurialis annua, Jasione, 

 Apera Spica-venti, &c. 



The enumeration of the stratified rocks of Berkshire may be con- 

 sidered to come to an end with the Bagshot Sands. Mr. Harrison 

 points out that if a boring were made near Easthampstead Plain it 

 would pass through many of the formations here described, till at 

 a depth of about 2,000 feet it would touch the first which was men- 

 tioned, namely the Oxford Clay, 



It will be well to allude in passing to the Sarsen Stones, or as they 

 are sometimes called the Grey Wethers, from a fancied resemblance 

 when seen from a distance to a flock of sheep. They are blocks of 

 sandstone or conglomerate, and are found most frequently on the 

 Chalk ; they are now generally considered to be fragments of some of 

 the Tertiary strata which once covered the district where they occur. 

 These harder portions remain while the softer part has been entirely 

 washed away. The blocks are often of considerable size ; in some cases, 

 as at Avebary in Wiltshire, they are as much as twelve to fifteen feet 

 across and about four feet thick. They are frequentlj^ found in villages, 

 where they may be sometimes seen placed against the corners of houses 

 to protect the walls from passing vehicles ; such a stone occurs at 

 Thatcham. The 'Nymph' or 'Imp' stone near Silchester is a Sarsen 

 stone ; its name may be derived from the letters ' imp,' meaning 

 Imperator, or from a figure of a nymph which may have been carved 

 on it. It is a milestone of great antiquity on the Spinae road near 

 Silchester. 



Another celebrated Sarsen stone is the ' Blowing Stone ' near 

 Kingstone Lisle, not far from the White Horse. It is about three feet 

 high, pierced with several natural holes, one of which, beginning at 

 the top and issuing at one side, can by a practised blower be made to 

 produce an alarm note, sufficiently loud to be heard under favourable 

 conditions as far as Faringdon, six miles away. A considerable number 

 are found in the neighbourhood of Ashdown, near the Wiltshire border. 

 Wayland Smith's Cave, which is doubtless a cromlech with an outer 

 circle, is also composed of Sarsen stones, from which the earth that 

 covered it was removed so long back as a,d, 955, since in a charter of 

 Edred it is referred to as Wei land's Smithy. 



Deposits of Post-Tertiary Age, The rock-groups, which have 

 been so far described, form so to speak the solid framework of the 

 land ; whichever of them is at or nearest to the surface in any district 

 may be spoken of as the ' bed-rock ' of that district. Over a large part 

 of the county they are covered by only a thin layer of soil, which is 

 itself made up mainly of the debris of the rock beneath. In such 

 a case it is the character of this rock that determines the nature of the 



