fiSS ' Martinis Geological Memoir^ and 



composition of the strata comprised within its area, apparently 

 anomalous, abundance of matter is afforded for speculation ; 

 and the controversy which has been elicited by these seeming 

 discrepancies, has occasioned much diligent research, and been 

 the means of illustrating, with more than usual perspicuity, 

 the geological details of this singular country. Messrs. Cony- 

 beare and Phillips, in their Outlines of the Geology of England 

 and Wales, Dr. Fitton and Mr. Webster in the Annals of Phi- 

 hsophy. Dr. Buckland and Messrs. Lyell and Murchison in 

 the Transactions of the Geological Society, and Messrs. Man- 

 tell and Martin in separate treatises, have severally contributed 

 to elucidate the principal phenomena of the Weald. But the 

 opposite opinions entertained by some of these writers, and 

 the undecided state in which they finally left the nomenclature, 

 after the "green sand" controversy, occasioned for a time 

 some little embarrassment to the geological student, from 

 which it is not, even now, very easy to be wholly free. These 

 difficulties have partly originated in the deviations, to which 

 allusion has been made, from the geological equivalents in 

 other parts of the kingdom, and in the interposition of depo- 

 sits, which, as far as we yet know, are peculiar to this district. 



Remembering that it is our province to render the matter 

 brought before the general reader as intelligible as possible, a 

 few explanatory illustrations of the ordinary arrangements of 

 the strata, drawn, not fi*om imaginary cases, but from authen- 

 tic sources, will prepare the way for a better consideration of 

 the Weald denudation. 



It need scarcely be premised, that the several masses, or 

 deposits, of clay, sand, chalk, and rocks, which contain organic 

 substances, appear in rotation upon the surface of our island, 

 gradually emerging from beneath each other, in regular order, 

 from east to west ; and that their truncated edges, particularly 

 in the outcrops of the harder strata, are elevated so as common- 

 ly to exhibit an abrupt escarpment towards the west, {fig, 105.) 



Angle of Inclination. Escarpment. Outcrop. 1 05 



Horizontal Plane. 



The most westerly is here the lowest stratum in the series, 

 and, of course, had priority of formation ; on the contrary, the 

 highest, towards the east, is the most recent. Such is the 

 prevailing order of the stratification, with reference to our own 

 country ; and it is observed that this arrangement is never 

 inverted : a never appears, for instance, in the situation of r, 

 nor changes place with b. The relation of certain beds to each 

 other being understood, and the position of any member of the 



