and qf Trap in different Parts of Scotland. 239 



bus" They are too often the result of conjecture, instead of 

 actual examination. 



It will not be amiss to point out a very few of the places 

 in Scotland where these unexpected masses of granite are 

 found. 



They occur both in districts of micaceous schist and of 

 gneiss, and they are even found, in more than one place, in 

 the middle of the old red sandstone. 



In the gneiss district, on the west coast, from Morven north- 

 ward, they are very common, as they are in the central parts 

 of Inverness and Ross-shire. About the sources of the Spey 

 and the Findhorn, such small masses abound often not exceed- 

 ing many square yards in dimensions. Even in Rannoch such 

 masses are found in a district of micaceous schist, and remov- 

 ed by many miles from any other similar rock. It is unne- 

 cessary to multiply examples ; and it would be equally unne- 

 cessary to offer this caution to any geologist, who has accu- 

 rately examined these tracts, as he cannot fail to have met 

 with instances of this occurrence. 



The chief difficulty of investigating granite, arising from its 

 want of stratification, is an equal source of toil in the examin- 

 ation of the trap-rocks. These also abound in Scotland ; 

 and, like granite, they are found, in some places, in large ex- 

 tensive continuous tracts, in others, scattered in very minute 

 patches, and separated by wide intervals. 



To connect these separated portions requires a different view 

 from that by which we attempt to reunite the scattered masses 

 of granite. These latter are judged, from all experience, to 

 be actually, and at present, continuous beneath the superficial 

 or incumbent strata. Trap lies above the stratified rocks ; 

 and, when discontinuous, it is so, either because it has been 

 originally deposited in that manner, or because the larger 

 masses, once continuous, have been destroyed in particular 

 spots so as to lose their continuity. Both of these are the con- 

 sequences of interesting geological causes which are not the 

 objects of consideration here. The fact alone is the subject 

 of the present discussion. 



Although trap is unstratified, it often possesses a peculiar 

 aspect, either in its outline, or in the nature of its vegetating 



