268 Martinis Geological Memoir, and 



The southern edge of this denudation forms the highest 

 crest of the chalk, Inkpen Hill being 1011 feet above the sea. 

 Its northern edge is less elevated, and the strata of the two 

 escarpments dip, in opposite directions, on each side of the 

 anticlinal line which passes along the centre of the valley. 



The interior consists of the green sand formation (glauconite 

 of Martin). The valley comprehended within the escarpment 

 is from four to five miles long, and from one to two miles 

 broad. Another, extremely similar, called the Valley of Ham, 

 occurs five miles to the westward, immediately under Inkpen 

 Hill, and is about half the area of that of Kingsclere. 



Many other valleys of this class, in the chalk and older 

 formations, are mentioned by Dr. Buckland, and our^y^. 113. 

 represents one of them in the Vale of Westbury, near Bristol. 

 Their drainage is generally effected " by an aperture in one 

 of their lateral escarpments, and not at either extremity of 

 their longer axis, as would have happened had they been 

 simply excavated by the sweeping force of rapid water ; and, 

 as it is utterly impossible to explain the origin of any valleys 

 of this description by denudation alone, or, indeed, without 

 referring the present position of their component strata to a 

 force acting from below, and elevating the strata along their 

 central line of fracture, I shall venture so far to involve this 

 theory of their origin with the facts which they display, as to 

 designate them by the appellation of Valleys of Elevation : of 

 course, due allowance must be made for their subsequent 

 modification by diluvial denudation." ( Geol. Trans., vol. ii. 1 23.) 



After reciting these examples, the author concludes : " The 

 facts, then, which we have examined, conspire to lead us to 

 the conclusion, that not only many enclosed valleys similar to 

 that of Kingsclere, but also, in a less degree, many open val- 

 leys similar to that of Pewsey and the great central valley of 

 Kent and Sussex, though largely modified by denudation, owe 

 their origin to an antecedent elevation and fracture of their 

 component strata ; and these phenomena may be regarded as 

 of frequent occurrence in the formations of all ages, and as 

 indicating the multitude of disturbing causes by which the 

 earth's surface has been affected." (Geol. Trans., vol.ii. p. 125.) 



Dr. Buckland adduces evidence to show that the superior 

 strata, which have been conceived peculiar to the basins of 

 London and Hampshire, were once continuous. Traces of this 

 union are observable in the detached portions which yet exist, 

 even on the highest eminences of the chalk formation. On 

 this hypothesis, which there seems little reason to dispute, the 

 London and plastic clays stretched uninterruptedly from the 

 coast of Norfolk to Dorsetshire, prior to the great era of the 



