124 The Flora of Wiltshire. 
that mark the close of the middle oolitic period.!. The rest of the 
district is cretaceous, embracing the major part of Salisbury Plain, 
forming an elevated platform. It also includes a considerable 
breadth of Upper Green sand, ranging westward from Devizes 
round the foot of the chalk hills, towards Westbury. This district 
is principally drained by the Upper and Lower Avon, the Wily, 
and Wily Bourne rivers. 
The scenery in this district is wild, consisting of a range of 
bleak downs and deep valleys, mostly bare of wood, presenting to the 
eye a surface checkered with cornfields and rich pastures. From 
Catley Hill we have one of the finest panoramic views in the county. 
The author’s list of plants for this district, the result chiefly of 
his own observations, is numerous, but much yet remains to re- 
ward any botanist, who will give it the careful and diligent ex- 
amination which it deserves. 
4, Tue Norra Western District. 
The north western district is bounded north by the Gloucester 
and Cheltenham Railway, commencing at Purton station, passing 
Minety to the station at Tetbury, and by the adjoining county of 
Gloucestershire; the counties of Gloucestershire and Somersetshire, 
respectively, forming its western boundary, its southern being 
formed by the Kennet and Avon canal, commencing at Freshford 
and terminating at Devizes, whilst its eastern is formed by tracing 
the highroad from Devizes through Calne and Wootton Basset, to 
the Cheltenham railway. The area occupies about 255 square 
miles. ’ 
The road from Devizes to Calne, cuts off some small portions of 
Gault and Lower Green sand at Rowde, Spye Park, Bowden Hill, 
and Sandy Lane. With this exception, the north-western district is 
oolitic, and has examples of all the strata, from the Kimmeridge 
clay to the Fuller’s earth inclusive. The Oxford clay is of con- 
siderable importance in this part of Wilts, occupying extensive 
levels round Melksham, Broughton Gifford, Chippenham, &e. It 
1 The average height of the coral rag hills seems to be about 400 feet above 
the level of the sea. 
