Buchland^s Formation of the Valley of Kingsclere, 253 



series being determined, we are enabled, with facility, to trace 

 the remainder. This rule is found to hold good in all practi- 

 cal examinations of stratified districts. The dip^ or angle of 

 inclination, is variable ; consequently, the surface, or the ex- 

 posed area, of any stratum is greater or less, according to the 

 angle that stratum forms with the horizontal plane. 



On examining any district composed of stratified rocks, and 

 intersected by valleys, it is commonly seen that the opposite 

 sides of those valleys exhibit corresponding strata, at elevations 

 governed by the dip {Jig, 106. a a a). 



106 



Where the beds are arranged above each other in this paral- 

 lel manner, they come under the denomination of conformable. 

 Where horizontal or parallel masses are placed upon inclined 

 strata, they are then stated to be unconformable. An example 

 is here furnished {fig, 107.) from a part of the Bristol coal- 

 field in Dr. Buckland's and Mr. Conybeare's section, repre- 

 senting the new red sandstone and lias reposing upon the 

 highly inclined coal measures. 



107 



Detached masses are frequently found capping the summits 

 of hills. These are called outliers^ and are obviously the re- 

 mains of beds whose intermediate parts are washed away, 

 leaving insulated portions, like mighty landmarks, to denote 

 the ancient extent of the strata. The intermediate spaces 

 that have been laid bare or hollowed out by the action of 

 water, are called valleys, or areas, oi denudation^ a phrase which 

 appears to have originated with the late zealous geologist Mr. 

 Farey. They are also styled valleys of erosion^ and these are 

 represented inj^. 108. 





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