Sandstone in the County of Forfar. 1ST 



tic variety of serpentine has also been in contact, on one side, 

 with the greenstone at the edge of the great dike, although it 

 has now wasted away and cannot be seen. 



If this conjecture be correct, the association of rock on the 

 Carity becomes still more analogous to that at Clunie; for, 

 in the latter case, are found greenstone, serpentine, and lime- 

 stone, whereas in the former, we should have greenstone, ser- 

 pentine, and dolomite. 



Although the two opposite banks of the Carity, which pre- 

 sent us with the sections which we have now considered in de- 

 tail, are not much more than fifty yards apart, yet they afford, 

 as we have seen, very different appearances, as far as regards 

 the junction of the serpentine with the stratified rocks. 



If we view the left bank alone, we perceive two parallel 

 dikes of serpentine, the first, 90 yards wide, the latter, in 

 which the dolomite abounds, about 25 yards in width. ' Be- 

 tween these are placed strata of shale and sandstone, highly 

 inclined, as also a vertical mass of conglomerate, much alter- 

 ed and indurated. But if we turn to the right bank, these 

 intervening stratified rocks appear to be entirely wanting; 

 and it seems that the two kinds of serpentine form one dike, 

 a thin bed of fine grained greenstone alone separating them, 

 and another bed of greenstone being also associated with the 

 dolomitic serpentine, towards its south-eastern edge. 



The phenomena which attend the serpentine at the West 

 Balloch enable us, in the first place, to add another fact in 

 confirmation of the geological connection, already observed to 

 exist, by other geologists, between greenstone and serpentine. 

 We are also presented with examples, more decisive than any 

 I have yet seen described, of stratified rocks affected by their 

 contiguity to serpentine, in a manner exactly similar to that 

 usually observed at their junction with trap dykes. We have 

 also pointed out in one place, a small portion of contorted 

 shale and sandstone, inclosed, and as it were entangled, in the 

 serpentine, as is often found in trap dikes, where they pass in 

 a similar manner through the regular strata. But what is 

 most striking in the general view of the section at the West 

 Balloch, on the left bank of the river, is the fact, that, while 

 on each side of the vertical mass of serpentine, the inclined 



