108 ON THE CONVOLUTIONS OF STRATA, &C. 



granite, has been converted into gneiss or mica-slate, or at 

 least into killas ; and this view is confirmed by the circum- 

 stance, that no example has been produced of granite veins 

 traversing sandstone. 



I expect, then, that granite and sandstone will not be found 

 to occur in immediate contact, unless where the latter has 

 been deposited upon the former. In the junction which is 

 seen in the bed of the river near Jedburgh, and in that at the 

 Siccar point, on the coast of Berwickshire, we see that the 

 sandstone has evidently been deposited in the state of loose 

 sand, on killas then existing as a hard and shivered rock. 

 We may easily conceive, that sandstone has been deposited 

 in a similar manner on the granite of second invasion ; and 

 that, in a similar manner, it has been consolidated and ele- 

 vated. 



I have not met with an example of this ; but such may be 

 looked for, and will be interesting in geology. I have just 

 learnt from a young friend, member of this Society, who has 

 spent a few days in the course of this year at the Cape of 

 Good Hope, that upon the side of the Table Mountain, a junc- 

 tion occurs of granite with killas, and that, higher up on the 

 hill, the same granite actually meets with sandstone. I hope 

 soon to have the means of laying before this Society the details 

 of these observations. 



III. 



