314 LIAS OF ENGLAND AND WALES : 
They may be seen near Bridport, on Brent Knoll, occasionally 
in the Cotteswold Hills, and some well-marked terraces have been 
noticed at Shenington, and Alkerton, near Banbury, and at 
Burton Dassett. They occur also near Tilton-on-the-hill. 
In these districts the terraces are found generally on the 
micaceous sands and clays, below the Marlstone rock-bed. 
Mr. E. A. Walford has attributed the terraced hill-slopes near 
Banbury to natural causes, partly to the slipping and sliding out- 
wards of the saturated porous strata upon the tenacious clays, 
aided by pressure of the superincumbent Rock-bed, and partly to 
the removal by chemical agency of calcareous matter from the 
beds.* I cannot accept this explanation. In all cases that I 
have noticed, these features terminate abruptly, and show no 
resemblances to the irregular terraces and broken ground due to 
landslips. The explanation that they are old terraces of cultiva- 
tion, is by far the most plausible one, and their occurrence on 
the slopes formed of the Middle Lias sandy clays, may be attri- 
buted to the fact that these tracts were found to be more fertile 
and more readily cultivated than the probably wooded tracts on 
the Lias clays. 
Over large areas of the Liassic " grass country," there is 
evidence that much of it was originally ''plough land," from the 
ridge and furrow due to former agricultural operations. In some 
parts of Leicestershire the old furrows are from one to three feet 
deep. 
Distribution of Population. 
The distribution of towns and villages on the Lias, as on other 
formations, bears a close relation to the means of obtaining a 
water-supply. 
In the tracts where the Lias is comparatively free from Drift, 
we find that the settlements were originally made near the escarp- 
ments, whether of the Lower Lias limestones or of the Marlstone. 
Springs issue from the base of the Lower Lias limestones and 
White Lias, and again more copious springs flow from the base 
of the Middle Lias " Marlstone,'' or from the underlying sandy 
beds. 
On the broad fiats of Lower and Middle Lias clay,, the few 
villages are usually very small, excepting in places where gravel 
occurs. 
Of the larger towns or cities placed for the most part on Lias, 
Bath is nearly surrounded by hills, that throw out many springs, 
and of course owes its development to its natural thermal waters. 
Gloucester is situated on gravel overlying Lower Lias; and Chel- 
tenham occupies a somewhat similar geological position, its growth 
being due to the mineral waters obtained by sinking to some little 
depth beneath the surface. 
Water-bearing Strata. 
On the Upper Lias clay, the villages usually draw their sup- 
plies of water from springs thrown out on top of the clay, at its 
* Journ. Northamptonshire Nat. Hist. Soc., 18^0. 
