in the Neighbourhood of Edinburgh. 231 



PART II. 



THE GEOLOGICAL RELATIONS OF THE FRESHWATER LIMESTONE 



OF BURDIEHOUSE. 



INTRODUCTION. 



Having in Part First confined myself to the description of 

 the limestone of Burdiehouse, considered as an individual bed 

 belonging to the carboniferous group, I shall now point out its 

 geological relations to other strata, both of an older and newer 

 date. 



The carboniferous strata, of which the limestone of Burdie- 

 house forms a very subordinate bed, appear in the great Low- 

 land valley of Scotland, which is watered by the Tay, the Forth, 

 and the Clyde. Some of these strata, particularly such as are in 

 contiguity with the limestone of Burdiehouse, I propose to con- 

 sider very generally ; first, in regard to their fractures, and, se- 

 condly, in regard to the remarkable alternations which they ex- 

 hibit ; and after these considerations, some important inferences 

 may be drawn concerning the geological relations of the fresh- 

 water bed, which forms the proper subject of this memoir. 



NOTES TO THE INTRODUCTION. 



Preparatory to entering upon any investigation of carboniferous strata, a few re- 

 marks on the older rocks to which the coal-fields of the south of Scotland have suc- 

 ceeded, may perhaps aid the inquiry. These I shall throw into the form of a note. 



No rocks are perhaps better calculated than those of Scotland to aid the inquiry 

 which has been undertaken by various geologists, with the view of determining the 

 extent of those convulsions of different periods, which have been attended with cor- 

 responding changes of level affecting the surface of our planet. Sometimes these 

 changes appear to have been the result of sudden violence, and, at other times, of a 

 gradual process of elevation or depression, carried on perhaps during the whole per- 

 sistence of a geological age, or system. An early elevation of the Grampian ridge, 

 for instance, appears to date from a period immediately subsequent to the formation 

 of such primary rocks as form the ingredients of the Scottish Alps, namely, talcose 

 schist, or primary clay-slate, mica-slate, gneiss, and their accompanying granites, 

 serpentines, or primary trap. 



