120 Rev. W. D. Cony beare's on M. de Beaumont's Theory 



almost unexplored, to pretend to offer more than a partial and 

 imperfect contribution to its investigation, requiring much ex- 

 tension, and probably many corrections, before it can be con- 

 sidered as having accomplished anything beyond a general 

 tnxcing out of the line of inquiry to be pursued. 



The first point in this inquiry is obviously to determine the 

 geological epochs to which the several elevations we observe 

 should be referred. Now we have direct evidence which 

 can enable us to do this, in very few cases ; those, namely, in 

 which, as in the Isle of Wight, we observe the immediate con- 

 tact of the strata affected by the elevating force, with those 

 which have been unaffected by it; and where moreover these 

 strata also are terms immediately following one another in 

 the regular geological series :— it is evident that this second 

 condition is no less essential to determine the exact geological 

 sera of the disturbance than the first; otherwise, where dis- 

 turbed and undisturbed strata of remote age are in contact, 

 the disturbing force may have acted during any portion of the 

 long interval which must have elapsed between the deposition 

 of the earlier and later formations : e. g. in the Boulogne di- 

 strict at Hardinghen we see the elevated strata of carboni- 

 ferous strata and coal at the foot of the horizontal sti'ata of 

 chalk ; and near Namur, in contact even with the tertiary for- 

 mations. Now it is evident, that so far as the indications af- 

 forded by these localities are concerned, the disturbing forces 

 may have acted at any time between the formation of the car- 

 boniferous rocks and the tertiary deposits ; and it is only by 

 extending our observations across the transition chains of the 

 Ardennes, — which appear to have been affected by the same 

 disturbances, and which abut on the South against undisturbed 

 horizontal strata of new red sandstone, muschelkalk and keu- 

 per, — that we can assign the epoch at the close of the cai'boni- 

 ferous pei'iod, and anterior to the formation of the new red 

 sandstone, as the probable geological date of the agency of 

 the disturbing force. 



In many cases, however, we are not thus able to trace the 

 disturbed district on any of its boundaries in contact with un- 

 disturbed beds immediately consecutive in age to some of the 

 disturbed strata; but are reduced to reason from the looser 

 analogy afforded by similar disturbances of the same rocks, 

 but in unconnected geological localities ; and it need not be 

 urged that we should be careful not to assign too much im- 

 portance to conclusions thus obtained. 



Again ; even as to the convulsions affecting the ver}' same 

 geographical district, it is too much to assume, without distinct 

 evidence, that they have all been produced by one single 

 shock, rather than by a series which may have occurred at 



