198 On Norfolk Island, 



red, porous, ferruginous earth, originating in the decom- 

 position of volcanic rocks (Wacke*) of ancient date, -which 

 occur in seams of various shades of colour like true strata, 

 and pass insensibly into hasalt ; of which, sometimes 

 columnar, the cliffs on the northern shore are formed. This 

 friable earth alternates with white concretionary marl, both 

 studded with boulders of porphyritic rock, gradually disin- 

 tegrating. This is evident by their outer layers crumbling 

 into dust under the finger, but gradually becoming denser 

 towards the centre, where their texture is as hard and 

 crystalline as granite. Pumice is found abundantly on the 

 coast. In fact, the whole geological character of the island 

 is indicative of volcanic agency. The low flat on the 

 southern shore, previously alluded to, about a mile in extent 

 from east to west, and a quarter broad, is alone of aqueous 

 origin. It consists of coarse marine limestone, or calcareous 

 grit of recent deposit, and is usually employed for building 

 purposes, but yields on burning lime of great purity. 

 Near this is also obtained sandstone, or calcareous grit of 

 fine quality, from which dripstones and other porous vessels 

 are manufactured. 



The only metal found on the island is iron, in the mineral 

 forms of red and yellow ochre. A chalybeate spring has 

 been noticed at Orange Vale. 



Phillip Island is about five miles distant from the Settle- 

 ment. It is I5- mile long, f ths of a mile broad, the general 

 elevation being greater than that of Norfolk Island, and 

 averaging 800 or 900 feet above the level of the sea. 

 In physical structure the two islands are identical, Phillip 

 Island consisting of porphyritic rocks more or less disin- 

 tegrated, and a small quantity of calcareous grit, known as 

 the Sloop Kock, on the shore. 



* Topograpliical and Medical Eeports, 1849-50. 



