(1) From the hill near Boxmoor Station.

(2) From the village of Wigginton, looking S.

(3) From the high-road between Graveley and Baldock.

(4) From Windmill Hill, Hitchin, looking W.

There were medicinal waters at Barnet, Northaw, Hemel Hempstead and
Welwyn, but these are now disused. Many other details touching
physiographical characteristics are mentioned as occasion arises in the
Alphabetical Gazetteer which follows this Introduction.

The Geology of Hertfordshire must be here summarised in few words. The
predominant formations are the Cretaceous and the Tertiary.

CRETACEOUS.--Ignoring the Gault, which barely touches the county, this
formation consists chiefly of Chalk-marl, Lower, Middle and Upper Chalk.
A series of Chalk Downs, an extension of the Chiltern Hills, stretches,
roughly speaking, from Tring to Royston, forming by far the most
prominent natural feature of Hertfordshire. The oldest rocks are in the
N.W.

_The Chalk Marl_ is superimposed upon the Gault and Upper Greensand
beds, which are confined to the western portion of the county. Its upper
layer passes into a sandy limestone, known as Totternhoe stone, which
has furnished materials for many churches in the shire. Ashwell, Pirton
and Tring may be named as neighbourhoods where this stratum may be
traced.