22 GEOLOGY OF THE LOTHIANS. 



neral of a bright red colour, and conglomerates are abun- 

 dant ; but, as the name implies, those of the white sand- 

 stone group are generally white, and conglomerates are com- 

 paratively rare. The shales accompanying the red sand- 

 stone strata, are of various shades of blue, green, yellow, 

 and red ; while those associated with the white sandstone 

 are generally grey : bituminous shale also is very rare in 

 the former series, while in the latter it is largely deve- 

 loped. The abundant diffusion of coal beds in the white 

 sandstone series, is another characteristic feature of this 

 group, for when these do occur connected with red sand- 

 stone, they are, with few exceptions, situated in what may 

 be considered as a debateable ground between the two 

 classes of strata, and in those portions which partake of 

 characters of both. Another rock which we have men- 

 tioned as occurring in the Lothians, is the Mountain Lime- 

 stone. This, as we have previously stated, is not here, as 

 in those districts of England or Ireland where it occurs 

 a distinct and separate formation. It occurs in the red 

 sandstone series of the Lothians, forming, in some loca- 

 lities, considerable beds, but its comparative scarcity in it 

 is to be considered as a mark eminently distinguishing this 

 series from that of the white sandstone group. 



Having now described the general relations of the various 

 secondary rocks of the Lothians to each other, we shall 

 enumerate their several mineralogical ranges of character. 

 The red sandstone, which we have mentioned as the fre- 

 quent occupant of the lowest part of the series, is in general 

 a fine aggregate of grains of quartz and felspar, held 

 together by a basis of ferruginous clay; scales of mica 

 are profusely distributed through it, and frequently, by 

 their great abundance, it assumes a slaty structure. A 

 coarse conglomerate forms a part of the red sandstone se- 



