66 GENERAL COMPARISON OF 



deposits scattered in so detached a manner throughout 

 BO wide an extent. If this be admitted, it will follow that 

 a great waste and removal of the strata must have been 

 effected before the present fragments could have been 

 separated as they now are found. 



Some important general questions here arise respecting 

 the connexion between the trap and the secondary strata, 

 as well as between that rock and the primary ; although 

 this latter is of comparatively trivial moment. It must 

 have been apparent, that whether the unstratified rocks 

 which so often accompany and interfere with the strata, 

 are present or not, or whether they are more or less 

 abundant, the general positions of these are in no wise 

 affected, even in cases where the trap is found clearly 

 intersecting them. It follows therefore that the present 

 position of the strata was determined by causes inde- 

 pendent of the trap, and prior to its formation. It equally 

 follows, that the disturbances which this substance has 

 caused in the secondary rocks, must have depended on 

 circumstances of a very limited and partial nature ; since 

 they are confined to a short distance from those points 

 where it is found either cutting through the strata or 

 sending branches into them. 



In the next place, no marks of disturbance are any 

 where visible, of such a nature as to have involved the 

 trap and the stratified rocks in one common movement, 

 or of such posterior displacements as have equally affected 

 both. No signs of general dislocation in short are any 

 where to be seen in the fundamental rocks, that do not 

 appear to have been produced previously to the deposition 

 of the unstratified substances. The trifling disturbances 

 caused by the trap veins are here, of course, excepted. 

 Hence arises the general regularity of the plane of 

 separation between the stratified rocks and the trap ; 

 and hence also may be derived the conclusion, that no 

 extensive changes in the disposition of the strata have 

 taken place since the formation of this substance. 



