Field. — On the Shifting of Sand-dunes. 561 



the relative length and thickness of corresponding bones 

 shows that the birds must have been of at least two varieties. 

 Among the bones are a lower jaw and part of the upper one 

 of the same bird. Moa-bones have also just been found among 

 the sandhills near Nukumaru, but so decayed that they would 

 not bear handling. In fact, people are hardly aware how 

 common such bones are, as they mistake them for those of 

 cattle or horses, and thus many finds are never reported. 



Aet. LIII. — On the Shifting of Sand-dunes. 



By H. C. Field. 



[Eead before the Wellington Philosophical Society, 8th July, 1891.} 



In reading the Transactions of the New Zealand Institute, 

 one often sees mention made of the shifting of sand-dunes 

 through the action of the wind ; but, except in a paper by 

 myself, read in Wellington in December, 1876, I have never 

 observed any estimate of the rate of such movements. I then 

 judged the rate to be about a chain in ten years on the north 

 side of Cook Strait, but it probably varies in different parts 

 of the colony ; and I think it would be well if persons in 

 various localities would note the rates which they have had 

 opportunities of observing, as we might thus get tolerably 

 accurate data from which to estimate the dates of past events, 

 particularly that of the extinction of the moa, which, so far as 

 I can judge, has varied very greatly in the several districts. 

 Possibly, therefore, the following i-esults of forty years' observa- 

 tion on the coast from Paikakariki to Patea may be worth 

 recording. 



My first experience of sandhills, on any scale, was when I 

 walked from Wellington to Wanganui in 1851. I had seen 

 such hills on a small scale in several parts of England, but 

 had no conception of their ever attaining the dimensions which 

 they do in New Zealand. As, however, I was a new-comer, 

 and there were so many novelties, in the way of strange birds, 

 shells, fish, vegetation, scenery, &c., to engage my attention, 

 the extent of the sandhills was the only thing which I par- 

 ticularly noticed. When I again travelled by the same route, 

 in the following year, I found a very noticeable change at one 

 point — viz., Otaki. In 1851 the river had run northwards, 

 parallel with the beach, for about a quarter of a mile, before it 

 entered the sea, and the accommodation-house ke|)t by the 

 ferryman was on the south or Wellington side of the river. 

 36 



