100 GEOLOGY OF THE LOTHIANS. 



through another, which, if it is not of as mechanical an 

 origin as the most modern detritus, could not, if it were 

 so, present any other suite of characters. Another point, 

 where we have found a greenstone connected with the sand- 

 stone conglomerate, is on the side of the road, near the farm 

 of the Brunt ; there is, however, nothing in its relations 

 different from those we have just mentioned. At Oldham- 

 stocks also, a great dyke traverses the sandstone, appearing 

 on both sides of the Stonecleugh burn, and also in its bed ; 

 no junctions of this rock with the sandstone are visible, and 

 throughout its whole extent it presents only the characters 

 of a basaltic greenstone. 



Concerning the relations of the transition rocks to the 

 unstratified masses, there are few points in the Lothians 

 where we have noticed any thing interesting, and the com- 

 parative rarity of such rocks in this group is, in some de- 

 gree, remarkable. The disturbed position of the second- 

 ary strata is, in general, referable to the presence of augitic 

 or porphyry rocks : the numerous flexures, however, which 

 are visible in the transition series, can, with few excep- 

 tions, be traced to visible masses of an eruptive nature. 

 To explain this appearance is, in the existing state of our 

 knowledge concerning the causes productive of mountain 

 chains, a subject of no little difficulty ; but it is not un- 

 likely that the great high land of the south of Scotland 

 has, as other chains, been elevated by actions of a more 

 general nature (as far as the mass of the globe is con- 

 cerned) than those which effect the protrusion of igneous 

 rocks. It has been proposed to explain the marks of 

 violence which are visible throughout mountain chains, 

 by the influence of innumerable earthquakes acting along 

 a given line, during a period of great duration. A geo- 



