118 GEOLOGY OF THE LOTHIANS. 



dimensions, and are almost universally traversed by a stream, 

 the magnitude of which depends on the angle which the 

 valley forms. If a stream is on the side of a mountain, it is 

 in general narrow, and cuts through a valley which increases 

 in breadth as it approaches the one, into which other moun- 

 tain streams discharge themselves. In regard to their 

 physiognomy, the secondary rocks of the Lothians present 

 appearances distinct from those of the greywacke group. 

 The red sandstone, which is the oldest member of the 

 secondary system of the Lothians, rises, at the western ex- 

 tremity of the Pentlands, and in the eastern part of the Lam- 

 mermuirs, into mountain masses, of a table-shaped or round- 

 backed form, and has, with the exception of some of the por- 

 phyry hills, an elevation next to that of the transition strata. 

 In the conglomerate districts, the valleys through which 

 rivers flow are almost entirely destitute of soil, and present 

 a more or less extensive deposit of the rolled blocks which 

 enter into their composition. The country formed of the 

 white sandstone series, when viewed generally, affords a 

 considerable contrast to that of the red ; when it is not 

 visibly affected by the ignigenous masses, with which it is 

 so generally connected, its surface is that of a very gently 

 undulating line, the depressions being trivial. At the west- 

 ern part of the Lothian coal-series, this comparatively level 

 position is reversed, inasmuch as the white sandstone rises 

 there, in the hills of Leaven Seat, Woodmuir Height, and 

 Muldrondrum, to the heights of 1164 and 1108 feet. 



The two great classes of unstratifled masses which occur 

 in the Lothians, exhibit, in a marked manner, the aspect 

 which characterises them in other districts. The hills 

 formed of the porphyry or felspathic class, differ from the 

 other mountainous parts of the Lothians, in the fact of the 



