110 GEOLOGY OF THE LOTHIANS, 



fragments of granite, syenite, greenstone, porphyry, mica- 

 slate, gneiss, quartz-rock, and varieties of grey wacke, which 

 are met with only in the central districts of Scotland, while 

 an examination of them shews, that they decrease both in 

 magnitude and frequency of occurrence as we advance south- 

 wards, a fact indicating that the aqueous currents (for to 

 such only can they be referred) diminished in intensity 

 as they were removed from the more central parts of the 

 island. Scattered around Edinburgh, numerous masses of 

 trap-rocks are met with, which appear to be derived from 

 no great distance. 



Near Ratho, there are diluvial clays in which rolled frag- 

 ments of greenstones, identical with those which occur in 

 situ, in the neighbouring hills, are abundant. Superimposed 

 on the limestone of Bathgate, and skirting the flanks of the 

 hills, which range onward to Linlithgow, diluvial deposits 

 of great thickness appear ; none of these, however, as far 

 as we have observed, contain masses of the primary rocks ; 

 indeed, it is probable that these clays have not been pro- 

 duced by the same current which distributed the numerous 

 boulders of old rocks over the Lothians. 



Of the diluvial class of clays and sands, the country 

 around Edinburgh exhibits several interesting examples. A 

 formation of sand and clay containing imbedded fragments 

 of older rocks covers up the country around Newhaven and 

 Leith, and extends as far as Joppa, in some places forming 

 high mural cliffs. In East Lothian, a very thick deposit 

 of diluvium may be observed, covering the rocky strata be- 

 tween the Dunglass and Bilsdean Burns, and consisting 

 entirely of rolled fragments of the various rocks of the dis- 

 trict, arranged in a more or less stratified manner : and 

 near the Siccar Point, lofty sandstone cliffs are surmounted 

 by a diluvial conglomerate, formed of rolled masses of the 



