28 GEOLOGY OF THE LOTH1ANS. 



The limestone which is associated with the red and white 

 sandstone formations of the Lothians, exhibits, throughout 

 its whole extent, a very limited range of characters. It is 

 usually of a grey colour, of different degrees of intensi- 

 ty ; its fracture is more or less conchoidal, with an earthy 

 aspect. In some quarters, as at Salton, Linton, and Sun- 

 nyside, the same limestone occurs of a reddish-brown co- 

 lour. In several localities, as at Bathgate in Mid-Lo- 

 thian, the limestone is associated with hornstone ; this mi- 

 neral forming in it numerous contemporaneous imbedded 

 masses, containing in some places silicified madrepores. 

 At Linton, jasper occurs similarly connected with the lime- 

 tone as the hornstone. The mountain limestone, in those 

 quarters where it is extensively worked, exhibits frequently 

 several alternations of a compact rock, with one having a 

 more or less perfect slaty structure, and containing a larger 

 quantity of argillaceous matter. It is in this imperfect 

 limestone that vegetable and animal remains are found in 

 the greatest abundance, and in certain districts it is charac- 

 terized by particular fossil bodies. At the Rhodes Quarry, 

 near North Berwick, the limestone becomes highly fetid. 

 This is the only point where such an appearance is to be 

 observed on a large scale, though, in several localities, as 

 at Salton, the same may be observed in one or more parts 

 of a stratum. 



In their organic contents the secondary strata of the Lo- 

 thians are in some respects remarkably interesting, and the 

 shortness of our remarks connected with them is not to be con- 

 sidered as indicating that these interesting bodies ought not 

 to receive much attention from naturalists. Their structures, 

 when viewed comparatively with living races, have unfolded 

 many highly valuable portions of knowledge in regard to the 

 ancient temperatures of our globe, its waters, and the circum- 



