SECONDARY ROCKS— MINERALOGICAL CHARACTERS, 23 



ries. It is of two kinds ; one variety, as we have before 

 stated, being entirely formed of variously sized masses of 

 grey wacke and its slates, and occurring in immediate connec- 

 tion with the transition ranges of the Lammermuirs ; while 

 another, which is met with only in different parts of the 

 Pentland district, and in the neighbourhood of Penny- 

 cuick, is composed of rounded masses of quartz-rock, grey- 

 wacke, flinty-slate, felspar, and common jasper, imbedded 

 in a base of similar fragments. At Danskin, in East Lo- 

 thian, and in the mountain valley of Glencorse, both con- 

 glomerates are well marked. The hills which occur on 

 both sides of Dunglass Burn, are composed of this rock, 

 which has resulted from the disintegration of the grey- 

 wacke, and the masses which form it are on such a co- 

 lossal scale, and held together so very loosely, that it might 

 be mistaken for a formation of very modern date. The red 

 sandstone forms extensive districts in Berwickshire, and 

 much of that part of East Lothian which ranges along the 

 northern front of the Lammermuirs. As that of several 

 other parts of Scotland, the red sandstone of the Lothians 

 is eminently characterized by containing in many places nu- 

 merous circular yellowish-green markings, in the centre of 

 which there is frequently a black coloured spot. Though red 

 is the predominating colour of the red sandstone series, still, 

 associated with it, there are other sandstones of various shades 

 of brown and grey. Variegated sandstones are abundant, 

 brown or red markings occurring in a field of white sand- 

 stone ; as examples of these, the sandstones of Salisbury 

 Crags and Dunbar are conspicuous. Interstratified with 

 the shales of the red sandstone series, clay-ironstone some- 

 times occurs ; it is, however, perfectly different in its charac- 

 ters from those clay-ironstones which are so abundantly in- 

 terstratified with the white sandstones and shales of the white 



