102 On the Transition Rochs of the Cataraqtti 



it not observable tbat it is cracked and fissured into huge irregular 

 tessera?, and that its surface presents the remarkable waved aspect 

 common to this rock in the vicinity. 



As few boulders lie on the west and south-west shores, the character 

 of the rock may here be seen to great advantage, whilst further east- 

 ward, the coast is so strewed with them, that its nature can be seen 

 only with difficulty. 



On this western shore, the limestone every where visibly over- 

 lies the granite; and may be observed in various ways. One of its 

 most curious features is that of a diin stratum (of only a few inches 

 in thickness) overlapping the granite for some yards. This stratum 

 is probably the crust which has resisted the weather. It covers the 

 granite as a paste would, and is very hard. Its color is greenish 

 blue, and it is highly calcareous, a very slight effort with an iron 

 point affording a very white streak. 



This change of color, from the usual grey or blue of the Catara- 

 qui limestone, appears to take place all along this shore, wherever 

 tlie granite and calcareous masses are in immediate contact, for on 

 proceeding to die south-west, as soon as we lose tins thin coating 

 over the granite and observe the other layers of limestone begin to 

 form a sort of low cliff, we perceive that the thin bed, which immedi- 

 ately overlies the sienite, becomes very dark, (of a deep blue green) 

 and that it is (at least at the outside) split into innumerable little cu- 

 boidal fragments resembling charcoal, but the strata directly above 

 present little alteration. 



After passing round the extremity of the Point, the granite is soon 



lost, but it evidently gives the shape which the hill above possesses. 



This hill is mostly covered with soil, on which rest small boulders, 



and presents towards the west end of its summh a new aspect. 



Here in excavating, a singular variation of the granitic aggregates 



was discovered, and which runs for some distance towards the north- 

 east. 



It is a very dark grey compound, composed of a paste of minute 

 grains, highly calcareous and traversed, in a beautiful manner, by 

 veins and knots of very red felspar. Where it has been uncovered, 

 its surface is wave-like, and furrowed by smooth and almost poUshed 

 channels following the direction of the ridge. Its hardness is so ex- 

 treme, that it is exceedingly difficult to work, although in small spe- 

 cimens its fracture is comparatively easy. The component parts ap- 

 pear to be felspar, hornblende, lime and quartz, and it exhibits bril- 



