CHALK rORMATlON. 
69 
The mountain ranges formed by the chalk are 
characterised by their smooth and unbroken out- 
line, and are generally covered with a short verdant 
turf* 
The earlier inhabitants of this island, either from 
choice or necessity, fixed their settlements on the 
elevated ridges and platforms of this formation ; 
and vestiges of their sepulchral mounds are still 
visible, scattered here and there over the Downs. 
Stonehenge and other druidical temples are situ- 
ated upon it, being composed of immense blocks of 
the siliceous sandstone, that occurs in the form of 
boulders on various parts of its surface. 
The description of the South Downs, inserted in a 
former part of this work, will sufficiently explain the 
range and extent of the Upper and Lower Chalk of 
Sussex. A^arying in altitude from 300 to upwards of 
800 feet, this chain of hills extends from Beachy 
Head along the coast to Brighton, from whence it 
stretches through the centre of Western Sussex 
into Hampshire. On the north it j)resents a pre- 
ci})itous escarpment to the Weald, but its southern 
side descends with a gentle slope, and on the south- 
west is lost beneath the beds of the Isle of AVight 
basin ; while the south-eastern part forms a line of 
chalk cliffs of considerable extent. 
* “ In Champagne, in France, tlierc are immense plains of chalk 
absolutely clestitute^of vegetation, except where patches of the Caicaire 
grossier occur as islands, or oases, in the midst of these deserts. Many 
parts of this tract have, perhaps, not been visited for ages by any living 
bcinir, no motive existing that could induce any one to wander there. 
This chalk is said to contain 1 1 per cent, of magnesia, to which the 
biu-renness of the soil is sup[)osed to be owing .” — Geological I'laiis-, 
aclions, vol. ii. p. 175. 
F 3 
