1869.] RATTRAY CAPE- YORK PElf INSULA. 301 



creeks of the neighbourhood, where the soil is more alluvial and the 

 vegetation more tropical. But even there it contrasts strongly with 

 its vigour and abundance further south, where the soil is formed of 

 the detritus of primary, metamorphic and sandstone rocks and shales, 

 the water-supply more copious, and both the physical geography, geo- 

 logy, and climate more favourable for growth. The diminutive ants 

 which abound here appear to prefer this ferruginous soil, which 

 they convert into a hard sun-dried clay, to construct their peculiar 

 pinnacled ant-hills, often 12 to 15 feet high, which form a conspicuous 

 feature on the hillsides and landscapes of the vicinity of Somerset. 

 It would be interesting to know whether or not this formation also 

 extends, like the two former, across Torres Strait into New Guinea. 

 Certainly a considerable patch of the southern part of that island 

 immediately opposite Cape York, is a blank in our most trust- 

 worthy geological maps, which may yet be filled up by the for- 

 mations now named. The overland expedition of the Jardines has 

 proved that this rock is found as far south, on the west side of the 

 mountain-range, as the Mitchell River ; and it probably extends 

 westward to the Gulf of Carpentaria, while on the east side of the 

 range it certainly exists as far as Weymouth Bay. According to the 

 E.ev. W. B. Clarke, of Sydney, this rock " is post-tertiary, as it 

 contains no gold ; otherwise it most highly resembles the common 

 ironstone in the auriferous rocks of iS^ew South Wales." A careful 

 assay of an average specimen made for me by his instigation at the 

 lioyal Mint of Sydney, in March 1865, showed that the ore con- 

 tained 39-69 per cent, of iron, but neither gold nor silver. Though 

 capable of yielding a fair per-centage of metal, the absence of coal 

 in the vicinity, the high price of labour, great distance, and cost of 

 carriage of the former to and of the smelted iron from the settlement, 

 will, however, long and perhaps always render this ore practically 

 unavailable. 



Lying between the volcanic rock beneath and the superimposed 

 Posttertiary ironstone, we find a more local and limited deposit in 

 the form of a coarse quartzose sandstone, having a wavy stratifica- 

 tion, and composed of attrited fragments of quartz varying from 

 ordinary sand particles to the size of a hazel-nut, imbedded in a light 

 clayey matrix, very friable and unfit for building when weathered. 

 Of this, several of the bold cliffs of Albany island and the opposite 

 mainland consist ; and these are so directly opposed, while the bluffs 

 and bays on either side would dovetail so accurately if brought to- 

 gether, that we may fairly conjecture that they were once continuous, 

 before the production of the huge cleft which now forms the Albany 

 pass, or the upheaval of the crystalline rock beneath, which was 

 doubtless the cause of this. A similar quartzose sandstone was also 

 found by the Jardines at various places along their route, and there 

 as here in connexion with ironstone. It would be interesting to 

 know whether a like formation exists in the adjacent part of New 

 Guinea. ISTo fossils have yet been detected in this rock. At the 

 north end of Albany island, where a boss of porphyry protrudes 

 and displaces the overlying sandstone and ironstone, fine examples 



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