386 ARUAN. GEOLOGY. SECONDARY STRATA. 



parts of these strata, such shells are found, truly placed 

 with regard to the plane of the bed, but not according 

 to their tendency to subsidence. These strata are there- 

 fore displaced, and it may thence be concluded, that 

 all the strata which follow them in a regular order, 

 have been similarly changed from their former to their 

 present position. There are but two modes in which 

 this change can have been effected; namely, by the 

 elevation of the ends next to the granite, or by the 

 depression of those most remote. If the often discussed 

 phenomena of the junction of granite and schist are 

 allowed to prove the elevation of the latter, it may 

 follow that the same cause has elevated the secondary 

 strata, and that the granite is posterior to them, as 

 it is to the schist.* The strong resemblance formerly 

 noticed between the greater part of this granite and 

 some of the overlying syenites, will perhaps add an 

 argument in favour of the same supposition. I have 

 pointed out the striking similarity between the syenite 

 of St. Kilda, that of Von Buch, and parts of the granite 

 of Goatfell. This similarity prevails through a con- 

 siderable space in the other mountains connected with 

 that hill. The resemblance between the syenite of 

 Benderig in Sky and the granite of Glen Catcol, is 

 equally striking, and the extent of correspondence greater ; 

 since nearly the whole of Ben vearan, Ben breach, and 

 Ben huish, consist of this variety. Hence it may be 

 conceived, that these different rocks may possibly be 

 of the same relative dates to the secondary strata ; 

 the only criterion still wanting to establish their identity, 

 being the presence of any portion of the granite of 



* It is under this supposition, that the junction of the red sandstone 

 and the granite, is an interesting object to discover; if indeed there 

 be a junction of these t\vo substances without the intervention of 

 the bchist. Should granite veins be found passing into the red sand- 

 stone as well as into the schist, this fact would be considered as 

 established ; at least as far as it is in the former case. 



