Dr. MacCullocH(>« the Geology of Glen Tilt, 271 



■original regular position and the posterior disturbance of these stra- 

 tified rocks. The limestone which is here visible, is a portion 

 of an enormous series of beds, which are to be found in a 

 regular position occupying the left ridge which bounds Glen 

 Tilt, interstratified with quartz rock and with different varieties 

 of schist. This regularity of position is destroyed wherever 

 these beds <:ome in contact with the mass of granite which oc- 

 cupies the right ridge before mentioned. Consequently, the 

 limestone involved in the sch'ist and granite now under review, 

 is a portion of a bed the original position of which is perverted 

 and lost. Are we now to suppose that this bed of limestone was 

 originally deposited in its present form with alternating layers 

 of granite ? Admitting that the reticulating v^ins have been the 

 consequence of a posterior intrusion, this cannot possibly be 

 true of the laminse, as independently of the difficulties, or im- 

 possibility as it may more properly be called, of such a pro- 

 cess, it is plain that the simultaneous flexure and contortion of 

 the laminated mass is the result of the disturbance produced by the 

 granite veins, and consequently that it was deposited before the 

 intrusion of those veins.* Must we then allow that there are 

 cases where granite, or a matter resembling it, has been deposited 

 like schist and bedded limestones from solution or suspension in a 

 fluid I In the mean time, however, the igneous hypothesis respect- 

 ing granite may perhaps allow of another mode of explaining this 

 appearance. It is conceivable that a mass consisting of alternate 

 layers of micaceous or argillaceous schist and limestone, a com- 

 pound of which abundant examples are seen in the immediate 

 vicinity of the rock under review, might be so acted on by heat 



* Vide Plates 16, 17. 



