THE OOLITE FORMATION. 



201 



again in the same position in a quarry about 100 feet higher 

 up the hill ; and as may be expected, the upper position is 

 the correct one. 



Now, to understand the causes of this displacement, it 

 will only be necessary to bear in mind that the pisolite is a 

 very hard compact rock, of the general thickness of about 

 ten feet, and this solid mass rests immediately upon beds of 

 soft clay (lias clay) ; it will hence result that the diluvial 

 action' subsequent to the upraising of this portion of our 

 island would of necessity carry away the soft underlying 

 clays, whilst the harder and more compact rock would fall 

 down the acclivities, and thus lead the inexperienced geolo- 

 gist into the belief that the oolite beds commenced much 

 lower than is actually the case, or that the pisolite was of 

 greater thickness than it is really found to be. 



I have been particular with this part of my subject, for 

 this reason, that on accompanying strangers to our hills, 

 they uniformly err in determining the proper commencement 

 of the oolite beds ; and even Mr. Conybeare, in the Geology 

 of England and Wales, fell into the same error with regard 

 to Bredon, an oolitic outlier, which stands out in bold relief, 

 dividing the vale of Evesham from the vale of Gloucester. 

 With reference to this hill, he says : " Bredon Hill is so 

 lofty, that it may be expected (for we are not aware that 

 it has been attentively examined) to exhibit a cap of the 

 great oolite'' Now, the truth is, that this hill is capped 

 with roestone, the second bed of the inferior oolite formation, 

 and its relative heights may be seen by referring to the 

 section. 



