266 AN ENQUIRY INTO THE NATURE OF [Ch. XIII. 



puting the original depth of such strata, we may be easily 

 deceived. If it be imagined, for instance, that a horizontal 

 series was elevated at different points in succession, so as to 

 preserve such a consecutive disposition, as might aptly be 

 represented by the teeth of a saw, it is plain that a very small 

 number of original strata would give rise to a great series of 

 inclined ones ; and that we might form a very false conclu- 

 sion respecting the real nature of such a series." Though 

 we shall object hereafter to this explanation, yet it must 

 be admitted, that when the repeated succession of a limited 

 number of strata, in consecutive order, occurs, their total 

 thickness must not be measured by the addition of the 

 dimensions of each stratum individually. But after every 

 allowance for such cases, the volume of primary slates and 

 fossiliferous rocks, which immediately follow each other, and 

 are inclined in the same direction, must still be very enor- 

 mous. Indeed, an actual calculation of their thickness would 

 perhaps furnish us with a datum, that would render the 

 supposed elevation more improbable than that of the inclined 

 gravel beds in the vicinity of Nice. 



Is it then to be concluded that strata have in no instance 

 been removed from their original position ? Certainly not ; 

 though at the same time it is very possible to account for 

 many appearances, which have been supposed to afford well- 

 marked examples of movement : the vertical layers of con- 

 glomerates have already been considered ; and the perpen- 

 dicular strata of unconsolidated sand and marl at Alum Bay, 

 in the Isle of Wight, may now be alluded to. It has been 

 stated, that sedimentary deposits may be formed on surfaces 

 inclined at considerable angles, and as the limits of this 

 mode of production have not been ascertained, we are not 

 prepared to say that it cannot, under particular circumstances, 

 extend to the perpendicular : besides, it is not requisite that 

 such deposits should be of great extent, as they may have 

 originally constituted only the descending portions of con- 

 siderable curves, the upper portions of which have been 



