59 
the Hampshire Downs in the east, which unite with another range of 
Downs, commencing with the cliffs between Weymouth and the Isle of 
Purbeck. This includes the north of Hampshire, and nearly all the 
south of Wiltshire; its longest diameter, from east to west, being 
about fifty-six miles, and its shortest, from north to south, about 
twenty. A part of this range may be said also to extend eastward as 
far as the Isle of Wight. These Downs are marked by a succession of 
rounded elevations ; and the chalk is often broken by valleys trans- 
verse to its strike, which is well seen in the North and South Downs. 
From the Marlborough Downs, the Whitehorse Hills and Ilsey 
Downs, the chalk is continued ito Oxfordshire ; it again makes its 
appearance, in a succession of Downs, through Buckinghamshire, 
Hertfordshire, Bedfordshire and Cambridgeshire, into Suffolk and 
Norfolk, rising again in hills near Norwich; it is continued to the 
coast, forming the cliffs between Cromer and Hunstanton. At this 
point the Wash breaks its continuity, but it re-appears on the opposite 
coast, forming the Wolds of Lincolnshire ; the stratum is then divided 
by the river Humber, but the chalk is discovered again near Hull; 
from thence it is continued through the Wolds of Yorkshire as far as 
Speeton, which is six miles from Flamborough Head, and the most 
northern extent of this formation. 
The Chalk formation is not observed in the western part of En- 
gland, in Wales, or in Scotland. In the north-east of Ireland it forms 
a compact limestone, but im a much more limited character, the deposit 
not exceeding 300 feet in thickness. 
In Lincolnshire and Yorkshire the chalk occasionally assumes a 
red appearance, probably from the presence of iron in a state of oxide. 
The highest elevation of the chalk is the Inkpen Beacon in Wilt- 
shire, being rather more than 1000 feet above the level of the sea*. 
* In Sussex the Ditchling Beacon is the highest point, being 856 feet above the level of the 
se€a. 
1 9 
