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A General View of the Phenomena displayed in the neighbourhood 

 of Edinburgh by the Igneous Rocks, in their relations with the 

 Secondary Strata ; with reference to a more particular descrip- 

 tion of the Section which has been exposed to view on the south 

 side of the Castle Hill. By Major-General Lord Greenock, 

 C.B.F. R.S.Ed. 



{Read 16th Dec. 1833.) 



The country in which Edinburgh is situated has no great 

 elevation above the level of the sea, presenting a gently undu- 

 lating surface, except where hills of igneous origin, in groups, or 

 perfectly insulated, rise abruptly through the strata, which con- 

 sist of the sandstones and shales of the coal-formation, with occa- 

 sional beds of limestone, which they overlie, and this country is 

 more or less covered by old and new alluvial deposits. 



The views suggested by these hills to the penetrating genius 

 of Hutton, who may be justly considered the founder of mo- 

 dern geology, first led to the knowledge of the true nature and 

 origin of the trap-rocks. Their analogy to those produced by 

 existing volcanoes, and the phenomena observed in their rela- 

 tions with the secondary strata, leave no doubt as to their having 

 been poured out from the interior of the earth in a fluid or viscid 

 state, through fissures in the strata occasioned by subterranean 

 convulsions — not, however, in the open air, like currents of lava 

 from recent craters, but in sheets or masses at the bottom of the 

 sea, their cooling and consolidation having evidently been slow 

 and gradual, under great pressure, such as might be produced by 

 a large volume of superincumbent water, as was ably illus- 



