BOTANY 



quantity on Westbury Wild, where the soil is a stiff clay, but I suspect a 

 strong Calcareous element is present. The scenery of the Great Oolite 

 district is much more diversified than that of the clay ; it is often well 

 wooded, and the ash is a conspicuous tree. One of the members of the 

 oolitic rocks, the Forest Marble, gives in Oxfordshire a home for some of 

 the chief rarities of the county, but this formation is only scantily repre- 

 sented in Buckinghamshire and chiefly near Thornton, Lillingstone 

 Lovell and Tingewick, and so far as I am aware without influencing the 

 vegetation. 



The Cornbrash is found in a more or less continuous band from 

 Fringford near the Oxfordshire border across the county to Newton 

 Blossomville on the eastern side ; it is nearly obscured by the Ouse 

 gravels east of Newport Pagnell, but near Beachampton it is two miles 

 across. This formation, which is well represented in Oxfordshire, consists 

 of various rubbly limestones sometimes, as near Buckingham, of a hard 

 blue character and associated with beds of blue and black clay, but the 

 limestone weathers rather rapidly, and in some of the quarries, as at 

 Thornborough, one can notice that the base consists of blue limestone 

 alone, but as the surface is reached the top beds are yellow and rubbly, 

 and this colour change is owing to the oxidation of the iron carbonate 

 which is present in the older and lower rock, it being gradually altered by 

 air and moisture into oxides of iron near the surface. There is a curious 

 inlier of Cornbrash at Marsh Gibbon in which we have a blue limestone 

 at the base, then a marly clay capped with loose rubbly stone. This 

 slight eminence is one of a series of similar ones which cross a part of 

 north Oxfordshire as an anticlinal line stretching from west to east, and 

 although not much raised above the plain of Oxford Clay in which they 

 occur, yet these dome shaped masses have been occupied by villages in 

 each case. As a rule the arable land on the Cornbrash is of a deep 

 reddish-brown colour and is well adapted for the growth of wheat, but 

 it produces few characteristic plants and the outline of the surface is 

 also somewhat featureless. On the village walls made of the local stone 

 at Marsh Gibbon, the stone crop (Sedum dasyphylluni) grows in one of 

 its very few homes in the county. 



The Oxford Clay so frequently referred to is a light-blue clay 

 weathering to yellow on the surface and of a great thickness, in many 

 places being over 500 feet. It occupies a considerable area of the north 

 of the county, forming a more or less undulating surface, uninteresting 

 from a scenic point of view, and without an attractive flora. From the 

 absence of springs, and from its impervious soil, there are fewer villages 

 on it, and it therefore is a sparsely populated area, so that the plants 

 which follow man and his operations are necessarily fewer ; but the new 

 industry of brick-making will probably introduce some species. The 

 contrast between its common constituents and those of the oolitic rocks 

 has been already alluded to, but as the Ouse has excavated into it for a 

 considerable portion of its course, the aquatic vegetation is the most 

 marked in character. Near Stoney Stratford the sweet flag (Acorus 



