Laing. — Chief Physiographic Features of Norfolk Island. 325 



mentioned. The coral-sandstone here extends from a quarter to half a mile 

 inland, and rises to a height of 30 ft. to 50 ft., with the strata lying hori- 

 zontal or dipping slightly, usually inland. According to Etheridge (p. 116), 

 the structure of this deposit is practically the same as the coral-sand rocks 

 found on Ascension and Lord Howe Islands :* " Touching the deposits at 

 Ascension and Norfolk Islands, their descriptions would almost embrace 

 that at our island. Of the former, Darwin says, ' It consists of small well- 

 rounded particles of shells and corals, of white, yellowish, and pink colours, 

 interspersed with a few volcanic particles. 'f Mr. Carne's description of 

 the latter is identical, almost word for word." The consolidation of this 

 rock is doubtless largely due to the percolation of rain through it. This 

 dissolves out carbonate of lime, which cements together the particles below 

 as it evaporates. Of the Lord Howe deposit, Etheridge {loc. cit., p. 124) 

 says, " When first I examined this deposit in situ I regarded it as of aqueous 

 deposition ; but after due consideration of all the facts for and against 

 I have abandoned this view in favour of an aeolian origin." Unfortunately, 

 I was unable to give much time to the investigation of this interesting 

 formation on Norfolk Island, but have no doubt that it has been formed 

 in the same way as on Lord Howe. My cursory examination of it did not 

 enable me to determine whether there have been two distuact periods of 

 formation, as at Lord Howe Island (Etheridge, p. 118, loc. cit.). 



The main body of Norfolk Island consists of streams of basaltic lava, 

 usually lying approximately horizontal. They are very much weathered, 

 so that it is difficult to get fresh specimens of rock. The whole surface 

 of the island except the rocky ridge of Mount Pitt and the precipitous por- 

 tions of its western slopes is covered to a depth of 150 ft. to 200 ft. with a 

 somewhat compact though porous layer of decomposed volcanic rock, 

 through which wells can be dug without much difficulty. These wells, 

 together with rain-water, provide the water-supply of the inhabitants. 

 The deepest well is near Bloody Bridge, and goes to a depth of 186 ft. 



This stratum apparently resembles the laterites of tropical regions in 

 some of its characters. Unlike these, however, it provides a very fertile 

 soil, often brown, and contains a grit, probably consisting largely of iron 

 segregated from the volcanic earths ; but, like the laterites, this surface 

 earth has none of the impermeability of a clay ; and, indeed, there is 

 probably no true clay on the island. What has led to this immense 

 weathering and decomposition of the volcanic rocks it is not easy to de- 

 termine ; but it can scarcely be doubted that it shows the island is by no 

 means of recent formation. It is, of course, impossible to determine the 

 age of Norfolk Island without data of a more definite character, and these 

 are at present wanting. 



Strewn over the surface of the soil in most parts of the island are 

 boulders of all sizes, evidently the remnants of the harder undecomposed 

 cores of the rock-masses. I was not able in the time at my disposal to 

 detect any old crater-vents or fissure-lines. Possibly the rocky ridge of 

 Mount Pitt may represent the portion of an old crater-wall. This lies 

 about a mile distant from the west coast, and roughly parallel with it, 

 and runs through the northern half of the island. Between Mount Pitt 

 and the sea the country is rather rough and considerably broken by cliffs. 



* " The Physical and Geological Structure of Lord Howe Island," by R. Etheridge 

 jun. (" Memoirs Australian Museum," No. 2). 



t Darwin, Geol. Observ. of Vole. Islands, 1844, p. 49. 



