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Transition Rocks of the CataraquL 



the limestone, with which they were once conjoined ; on the left, is part 

 of the beach of calcareous and siliceous shingle, and on the right is a 

 peculiarly large rounded mass of sienite, on which the observer may 

 sit, resting one hand behind him on the limestone, whilst his feet are 



on the same rock. 



The variolous aspect of this conjoined rock is fully as distinct and 

 vivid as that of the otherwise imperfect sketch we have given above, 

 and immediately strikes the most listless observer. 



The transition limestone here alters its nature into a porphyritic rock, 

 as the tables are composed of the usual dark calcareous matter, thick- 

 ly studded, throughout their masses, with nodules and strings of quartz, 

 which, on a polished surface, have a bluish lustre and are very beauti- 

 ful. I have had some of the rock blasted on the beach, near this place, 

 where there is a most interesting mingling of the rocks in every 

 variety of form, which we could suppose a state of jelly or of fusion 

 could create, and I have found the quartz penetrating the calcareous 

 matter, in every direction, as if shot into it ; amidst this mass, a few 

 crystals of pale feldspar appear, but not numerous enough to give a 

 decided character to the mixture. The feldspar indeed, as before 

 noticed, appears to have a decided antipathy to the lime, as the sienite 

 nodules which are interspersed, have, generally, a protecting coat of 

 quartz around them, whilst the feldspar, of a bright red, remains un- 



4 



disturbed. 



