GEOLOGICAL STRUCTURE OF SUSSEX. 21 



III. 

 GEOLOGICAL STRUCTURE OF SUSSEX. 



The investigation of the geological structure of this district is attended 

 with considerable difficulty. The displacement and disintegration which 

 some of the strata have sustained; the excess of soil and vegetation with 

 which in many places their basseting edges are covered at the Hne of 

 junction ; and the absence of sections in those situations Avhere the re- 

 lative position of the rocks is involved in obscurity, present numerous, 

 and, in some instances, insuperable obstacles, to accurate examination. 

 Under such circumstances, induction and analogy must supply the place 

 of actual observation ; but the relative position of the principal masses 

 having been correctly ascertained, whatever errors may have originated 

 from the causes alluded to, are of minor importance ; since they chiefly 

 relate to the geographical extent of the strata, and cannot affect the 

 geological deductions that may be di-awn from these researches. 



For the information of the general reader, it may be necessary to ob- 

 serve, that in Sussex, as in every other part of England, the strata main- 

 tain a certain order of superposition, and that however great the displace- 

 ment or interruption they may have sustained, this order is never inverted. 

 To illustrate this remark, we may observe, that the blue chalk marl, v.hich 

 separates the grey chalk marl from the green sand at Hamsey, Ringmer, 

 and Laughton, is altogether wanting at Eastbourne, and several other 

 places; but in these instance the grey chalk marl reposes immediately upon 

 the green sand, the relative position of the masses remaining unaltered, by 

 the absence of the intervening deposit. 



The following arrangement of the strata of the south-eastern division 

 of Sussex, is that which, after much reflection, I have been led to consider 

 as agreeable to their natural order of succession. 



