i8o 



HARDWICKE'S SCIENCE-GOSSIP. 



Fig. 123. 



Navan. 



Alhhcn 



'alhriggccn 



Skerries 



Lambay 

 1st. J 



o 000 



> c o o 

 0000 



a <i < 



Coal Measures 

 Cambrian 



+ + + 



Cxrbom/ervas 

 Limestone 



URca Schist 



T7\ Old Red 

 •"•".■ Sandstone 



r± a^ /°* 



y*\ /V ^ 



a a- /\ /» TrapJiock 



X X X X 

 X X x x * 

 X X X X 



Lower Sxhxruxn. 

 Grardle. 



GEOLOGICAL MAP of the NEIGHBOURHOOD of DUBLIN. 



the prominences which are called " the Burnt Rock," 

 "the Lover's Leap," and "the View Rock," are of 

 quartz rock, associated with the Cambrian formation. 

 The well-known Powerscourt Waterfall, nearly 300 

 feet high, in the same river, is about four miles south- 

 west of Enniskerry, in the Powerscourt demesne, 

 where the metamorphic rocks are prevalent. 



Of the stratified or sedimentary rocks the lowest 

 Palaeozoic formation is the Cambrian, which is com- 

 posed of green and purple grits and slates, often 



interstratified with masses of dull yellow or brown 

 quartz rock, and having a total thickness of several 

 thousand feet. 



Strata of this character form the bold and rugged 

 headland a little south of Bray, rising to a height of 

 793 feet. The outline of these hills when viewed from 

 the north is very picturesque, with the prominent 

 peaks of the Great and Little Sugarloaf Mountains 

 (formed of quartz rock), in the background. The 

 Great Sugarloaf, four miles south-west of Bray, rising 



