GENERAL DESCRIPTION. 



THE LOTHIANS. 



That portion of Scotland, which is bounded on the north 

 by a line drawn from the Firth of Forth to the Firth of 

 Clyde, is composed entirely of rocks of the Secondary and 

 Transition classes. The former of these is traversed by ig- 

 nigenous masses of the Felspar and Trap families, while the 

 latter, besides being connected with these rocks, is broken 

 through in several places by different granites and syenites. 

 As it very generally happens that the oldest rocks of a 

 country are those which attain the greatest altitude, while 

 the newer formations which skirt them, form, according to 

 their relative ages, either the hilly or the low land ; so here, 

 the mountainous districts are composed of the older rocks, 

 viz. the grey wacke and transition slates (strata, which con- 

 stitute the more or less uninterrupted high land which ex- 

 tends from St Abb's Head to Port Patrick in Wigtonshire), 

 while the plains and less elevated country, exhibit only rocks 

 referable to one of those groups which collectively form the 

 great series of secondary formations.* All the strata of 

 this class, which occur in the southern division of Scot- 

 land, are to be referred to the carboniferous group. In 

 several details these rocks will be found to differ from the 



* The geognostical characters of the great high land mentioned in the 

 text were first made known by Professor Jameson, who, indeed, was the 

 first geologist who pointed out the occurrence of Transition rocks in Great 

 Britain. 



