George Clinch—Sculpturings of the Chalk Downs. 55 
In the discussion to which Mr. Reid’s paper gave rise, the most 
remarkable view on the subject was expressed by Professor Seeley, 
who attributed the Dry Valleys mainly to marine erosion. He sug- 
gested, too, that the deposit of Clay-with-flints had been swept into 
its present position by ‘tidal waves’ at the time when the land was 
being submerged and the waters were working up the valleys. 
Sir A. Geikie remarked that the valleys were doubtless outlined | 
before the Chalk was exposed at the surface, and then subsequent 
erosion in the Chalk had been effected by solution and mechanical 
abrasion under conditions which have now disappeared. 
Topley referred the origin of Dry Chalk Valleys to the action of 
‘running water’ on land that was solidly frozen. 
It will be observed that several authorities were inclined to ascribe 
the origin of the valleys to the erosion of running water. Seeley’s 
theory as to marine action may be dismissed, perhaps, as lacking both 
proof and probability, but Topley’s sug gestions as to ‘ running water’, 
and Mr. Reid’s as to summer floods, are, I venture to think, scarcely 
less inapplicable. 
If water, even in the form of ‘mountain-torrents’, as Mr. Reid 
suggests, was the excavating force, we should expect to find (1) a 
sufficient watershed, (2) terraces on the sides of the valley repre- 
senting different stages in the volume and velocity of the torrent, and 
(3) a deposit of hard and insoluble matter, such as flints and other 
debris of the Chalk. The first and second of ‘these features ¢ are lacking, 
and the third is by no means constant. 
Since the publication of Mr. Reid’s paper geologists Nee suehi in 
other directions for explanations of the Dry Chalk Valley systems. 
One of the theories most in fashion in recent times is that known as 
the ‘solution’ theory, by which pluvial activity is invoked, and the 
whole of the phenomena of Chalk sen ippunines is by some! referred to 
the solvent influence of rain and atmosphere.’ 
The direction of the Dry Valleys, we are told, was ‘doterasined by 
the courses of streams and rivers on the surface of. the Chalk plateau 
in remote times. The effect was to remove the clay capping and thus 
lay bare the soluble Chalk to the influences of rain and atmosphere. 
Every part which was bereft of its clay protection became-in time, 
after a long series of years, hollowed out into valleys. 
I am bound to say that this theory, ingenious as it is, gives; to my 
mind, far too great importance to (1) the solubility of the Chalk, and 
(2) the influence of rainfall. Indeed, I think such a theory ‘is insuffi- 
cient to account for certain definite and fairly constant characteristics 
of these sculptured channels, the most important and obvious of which 
are (1) the sinuosities of the valleys, (2) their elaborate and compli- 
cated forms, (3) the general downward inclination of the valleys 
towards their outlets, and (4) the presence of rolled chalk, flints, etc., 
in the valleys themselves. 
That erosion rather than solution was the active foree in the 
formation of some of the dry chalk valleys is shown ‘by deposits 
of high-level gravels having been cut through. Now, it is obvious 
1 See G. W. Young, Proc. Geol. Assoc., 1905, vol. xix, p. 191. 
