xx FLORA OF OXFORDSHIRE. 
The Chalk. The most striking feature in South Oxford-. 
shire is the bold chalk escarpment stretching in an indented 
line of considerable beauty from Goring to Bledlow, at Nuf- 
field rising to 698 feet and at Chinnor to 809 feet. The 
table-land is split up into many branching dry valleys. North 
of Watlington are three outliers, at Gilton hill, at Adwell 
where there is a tumulus, and another to the north-west of 
Pyrton. The junction of the lower chalk with the green sand 
is well marked by a line of springs about which have been 
built the pretty villages of Mongewell, Shierburn, Lewknor, 
Aston Rowant, Chinnor, and Bledlow, the latter being especially 
interesting. 
The Lower Chalk is usually rather darker in colour than the 
Upper and has but few flints. It is about goo feet thick and 
constitutes all the chalk country north of the escarpment, up 
which it extends for some distance, as also along the large 
valleys which have been worn through it. Between the Lower 
and Upper Chalk occurs a hard rock called the Rock band, 
which forms the crest of the Chiltern Hills. It never contains 
flints and varies from 3 to 7 feet in thickness. On this rests 
the Upper Chalk, about 300 feet thick, containing flints in large 
numbers always in the planes of bedding. This Upper Chalk 
stretches to the east and south as far as the county boundary. 
The plants limited to the chalk include Linaria repens, Fu- 
maria Vaillantit, Orchis simia and militaris, Cephalanthera 
ensifolia, Gentiana germanica, Iberis amara, Hypericum mon- 
tanum. 
Tertiary Period. The Eocene is represented by outlying 
fragments of the Reading beds in the form of mottled, tena- 
cious clays, free from calcium carbonate, generally arenaceous. 
At Nuffield there is a small patch of sand on the highest part 
of the hill. On Watlington hill they exist as light brown 
coloured sand and clay with rounded flints. It is evident that 
these Reading beds once covered the chalk from which they. 
have been removed by denudation, traces of them are found 
about Hailey wood, and at Stokenchurch a plastic clay belongs 
to this formation. Other outliers exist at Stoke row, Tur- 
ville common, Woodcote common, Maidengrove, Hollandridge, 
Ibstone, and Nettlebed, the latter being capped by London Clay. 
