85 



lines of a slightly different colour and texture pass across 

 irregularly, incontinuous and not perfectly horizontal, these 

 consist generally of washes of slightly different materials, 

 a little more sand alternating with a little more clay being 

 the usual cause of the difference. These irregularities 

 give the deposit a wavy lenticular character and shew 

 that it is the dry land wash of rain as distinct from a 

 deposit laid under water ; it contains occasional pebbles 

 irregularly placed. This material is known generally as 

 virgin in contradistinction to vegetable soil. It is by 

 some called "Warp," which if used should be qualified. 



As each recurrence of glacial denudation obliterated 

 the evidence of former 'ones on dryland, we cannot ex- 

 pect to find signs of earlier ones except under peculiar 

 circumstances (as in the Darenth Brickearths), and this 

 obliteration has especially affected the rain-warp, the last 

 deposit of which has almost everywhere lost its distinctive 

 character. [See PL '\. fig. i.) 



Beneath this loam is found a layer of soil consisting 

 commonly of stony blocks derived from the broken and 

 weathered masses of the stratified rocks, with softer clays 

 and sands all mixed up together. 



At first view these particles appear confusedly mixed, 

 and it is perfectly clear that they are not water laid. Most 

 of the particles are so arranged that their long axes are 

 far from horizontal or shewing " bedding " as would have 

 been the case had they been laid by water. There are two 

 ways of looking at this layer, if so it may be called, which 

 will resolve the apparent confusion into a regular struc- 

 ture. 



In the most suitable places for studying it, as in the 

 softer rocks of the pleistocene period, if a vertical section 

 be made in the direction of the slope of the ground, the 

 stratified layers below will be observed to be bent with 

 pear-shaped curves and folds, the upper portions of which 

 folds and curves are inclined and bent in the direction of 

 the lovver ground, this is underplight. (See figures at the 



G 



