cliv 



Report of the Mineralogical Survey 



[No. 126^ 



primary limestone, mica slate, and lastly gneiss, all resting, and in this 

 order, on a secondary conglomerate ! 



330. Are we then to say that this latter is really the case, and that 

 even those facts most generally received, and as yet disputed by no 

 school or sect however sceptical, are often all but partial and local occur- 

 rences, and not examples of a general law applicable to every country ? 

 Or is there any way of viewing the subject by which we may escape 

 from so startling a conclusion ? Will any dislocation, subsidence, or 

 elevation of the strata explain the difficulty ? I think not ; for besides the 

 enormous extent of the fault which we must suppose to account for the 

 schistose strata, (at least eight miles in thickness and thirty in breadth,) 

 appearing to dip beneath the gneiss strata, a fault which startles the 

 imagination by its magnitude, we have also to believe, that at each 

 junction of two different formations, a similar fault occurred. This 

 is an assumption evidently gratuitous, and not having even a seeming 

 of probability to recommend it. And in two instances, probably in 

 many more, the appearances as described leave no doubt as to the 

 fact of the newer rocks lying under the older ; that is, if we 

 suppose the strata continuous underneath. In these instances, no 

 dislocation whatever will explain the anomaly. The difficulty appears 

 to me to be real, unless we give up those views of stratification which 

 would identify them with the parallel and consecutive layers of mecha- 

 nical deposition. 



331. It is an opinion gaining ground every day amongst geologists, 

 that the seams of stratification are not always what they have been 

 supposed, — the effect or sign of mechanical subsidence ; and many other 

 facts besides this, militate against the supposition we are considering. 

 Were those layers really deposited from a fluid by the effect of gravity, 

 how are we to explain the sudden changes which are often seen 

 to take place in strata, not vertically, but horizontally, and this repeated 

 often in a very limited space. ? That what is called concretionary 

 structure may sometimes produce parallel seams, we see in the case 

 of those clay slates in which what are supposed to be the planes 

 of stratification, are not parallel with the schistose planes. And that 

 parallel seams, not to be distinguished from those of stratification, 

 may originate in some other cause, is also obvious from the fact 

 so often observed of two, and even three sets of these seams occurring 



