Granite of Aberdeenshire. 36 



for want of local references. In these, it is easy to see the 

 transition which takes place between the common granite and 

 these greenstones ; and the further change, by which the 

 coarser greenstone becomes a basalt, or assumes an uniform 

 texture in which the separate minerals are no longer distin- 

 guishable. If any suspicion had remained that these were veins 

 of trap traversing the granite, they would have been completely 

 removed by examining tlieir forms, their connexions with that 

 rock, and the frequent and imperceptible transitions which oc- 

 curred between the two ; transitions precisely similar to those 

 which take place where ordinary granite changes its character, 

 either by varying its composition, or by an alteration in the 

 nature of its texture. 



On a further investigation, it was found that the rocks of this 

 character occurred in very considerable tracts ; irregularly in- 

 termixed with the common granite, in such a manner as to 

 €qual it in quantity, and to remove all possibility of hesitation 

 respecting their continuity and their community of geological 

 origin and position. 



It was already remarked, that a part of Bennachie consisted 

 of an ordinary granite, in which the ingredients, and more 

 particularly the quartz and felspar, were frequently crystallized. 

 On the northern face of this mountain, the rocks in question 

 occur in great abundance ; passing into the common granite, 

 and forming, in some places, an equally large proportion of the 

 general mass. The want of artificial sections, prevents the 

 transitions from being here seen as clearly as in the places last 

 described ; but there is still no difficulty, by the use of the 

 hammer, and with proper attention, in confirming the truth of 

 those views on which it is now unnecessary to dilate any 

 further. 



It only remains to describe the mineral characters of the 

 rocks which have thus been shown to form part of the general 

 mass of granite in this country ; and that description will still 

 further show the analogy which, in so many othev important 



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