370 Transactions. — Geology. 



Besides these specimens there was — 



5. A portion of bone, fin. in length, remarkable for the 

 smallness of its medullary cavity and for the density and 

 thickness of its walls — a fragment which I am in doubt 

 whether to assign to a bird or to a reptile without the oppor- 

 tunity of microscopic examination. If it be a bird's bone it is 

 neither a moa's nor an Apteryx's. 



Some time after my visit to Timaru Mr. Hardcastle, of 

 that town, was kind enough to send me a block of the dolerite 

 having imbedded in it a portion of a x^seudomorph of a round 

 block of wood, originally measuring, he tells me, loin, long by 

 Ifin. in diameter, which had been entombed in the lava- 

 strearn.* 



As I have remarked above, the orfi>'lying bed, A (v,'hich I 

 find it difficult to distinguish by any marked characters from 

 tlie bed underlying the dolerite), presents all the characters of 

 the cla}"-depo3it on the hills of Banks Peninsula. The origin 

 of this clay in different parts of Canterbury has been ascribed 

 (1) to marine deposit at the mouths (it is suggested)! of "the 

 great rivers ; " (2) to the same agencies by which Eichthofen 

 has explained the vast deposits of loam — the loess — in China — 

 namely, by subaerial denudation and (chiefly) by the accumu- 

 lation of the dust carried by the wind across the land, which 

 is retained by the grass, whose roots also, in decaying, assist 

 in raising the level of the ground. 



To the marine origin of this formation I am entirely op- 

 posed, as it appears to me too extraordinary that a clay 

 ca.pable of preserving the fine tubuli (supposed to be the vacant 

 moulds of decayed roots) should not have preserved a single 

 stray leaf or a fern-frond ; and that a current which was 

 dropping down heavy moa-bones here and there should not 

 also have deposited a branch or a, fern-stem, or small pebbles 

 in its course ; and that there should be so remarkable an 

 absence of unmistakable water stratification. That portion 

 of Professor von Haast's theory wliich ascribes the accumula- 

 tion of this loess to subaerial decomposition of the underlying 

 volcanic rocks appears to me to be the sounder theory. But 

 that it owes much of its depth to windborne dust seems to me 

 very improbable, for the loess occurs abundantly on the seaward 

 as well as on the landward side of the hills. In his "Geology of 

 Canterbury and Westland," page 356, von Haast, speaking of 

 the strata traversed in the construction of the Lyttelton tunnel, 

 observes, " This bed of loess changes gradually before vve reach 

 the volcanic rock to a true slope-deposit, consisting of fragments 



* This has beeu submitted to Sir James Hector for analysis at the 

 Colonial Laboratory. 



t Hutton: Trans. N.Z. Inst., vol. xv., p. 413. 



