chap. i. Calcareous Deposit, 13 



The basaltic lava, superincumbent on the calcareous 

 deposit. — This lava is of a pale gray colour, fusing 

 into a black enamel; its fracture is rather earthy 

 and concretionary ; it contains olivine in small grains. 

 The central parts of the mass are compact, or at most 

 crenulated with a few minute cavities, and are often 

 columnar. At Quail Island this structure was assumed 

 in a striking manner; the lava in one part being 

 divided into horizontal laminae, which became in another 

 part split by vertical fissures into five-sided plates ; and 

 these again, being piled on each other, insensibly 

 became soldered together, forming fine symmetrical 

 columns. The lower surface of the lava is vesicular, 

 but sometimes only to the thickness of a few inches ; 

 the upper surface, which is likewise vesicular, is divided 

 into balls, frequently as much as three feet in diameter, 

 made up of concentric layers. The mass is composed of 

 more than one stream ; its total thickness being, on an 

 average, about eighty feet : the lower portion has cer- 

 tainly flowed beneath the sea, and probably likewise the 

 upper portion. The chief part of this lava has flowed 

 from the central districts, between the hills marked 

 A, B, C, &c. in the woodcut-map. The surface of the 

 country, near the coast, is level and barren ; towards 

 the interior, the land rises by successive terraces, of 

 which four, when viewed from a distance, could be 

 distinctly counted. 



Volcanic eruptions subsequent to the elevation of 

 the coasiland ; the ejected matter associated with earthy 

 lime. — These recent lavas have proceeded from those 

 scattered, conical, reddish-coloured hills, which rise 

 abruptly from the plain-country near the coast. I 

 ascended some of them, but will describe only one, 

 namely, Red Hill, which may serve as a type of its class, 

 and is remarkable in some especial respects. Its height 



