134 GEOLOGY OF THE LOTHIANS. 



is in one or two places arranged in an irregularly tabular 

 manner. The structure of Easter Lomond is precisely si- 

 milar to that of the two hills we have just described, and 

 in no place are there any appearances which render a de- 

 tailed description necessary. Throughout the whole extent 

 of this highly picturesque and beautiful range of trap hills, 

 no point can be fixed on as one through which the igneous 

 matters which alternate with and cover the sandstones have 

 been erupted : the almost perfect horizontality of the strata 

 is, however, a sufficient indication that these trap-rocks are 

 to be considered more or less as portions of plutonic streams, 

 which, on being erupted, have flowed over horizontal sur- 

 faces. Separating the hills of Wester and Mid Lomond, 

 there is a ravine which is interesting, inasmuch as it has 

 evidently been produced by a great rent running through 

 the parallel and horizontal beds of aqueous and igneous 

 rocks, which form these hills: no one, however, when viewing 

 them, and observing the perfect agreement of the beds of the 

 one hill with those of the other, can ever consider this ravine 

 as original, nor can any one, with any degree of propriety, 

 refer it to the action of the rivulet. When describing the 

 trap-rocks in the vicinity of Edinburgh, we have remarked 

 that they, as well as the strata on which they repose, fre- 

 quently present abrupt and broken fronts : of this the 

 Lomond hills on their northern side exhibit an excellent 

 example ; and the horizontality of the beds renders it pro- 

 bable that this aspect has been produced contemporaneous- 

 ly with the protrusion of the ignigenous masses. 



We have now described at considerable length the geo- 

 logy of the Lothians, having endeavoured to notice every lo- 

 cality which in our investigations appeared worthy of detail, 

 and every rock which afforded to us any thing interesting, 



