414 Transactions.- — (ecology. 



Geraldine Downs — which in all probability was emitted simul- 

 taneously with the Timaru dolerite — is covered by a bed of 

 clay several feet in depth. I have not examined this with 

 instructed eye, but, as it could have been deposited in no other 

 way, its origin may safely be declared to have been similar to 

 that of the Timaru loess. It is a stiffer, " colder" clay than 

 this of Timaru, and this fact may be accounted for by differ- 

 ence in the character of the dust supplied to the winds which 

 formed it. I cannot doubt that examination of the loess on 

 Banks Peninsula (described by Professor Hutton as aqueous) 

 would result in like proofs of its subaerial origin being obtained. 

 Other loess-fields in Canterbury would doubtless furnish similar 

 evidence. 



The descriptions I have read of the great loess-formations 

 of the Ehine and of the " terrace " formations of North 

 America, the origin of which, I understand, still puzzles Euro- 

 pean and American geologists, suggest to me in every detail 

 that the dust-heap theory which explains the Timaru loess 

 will also perfectly explain them. 



In a small volume on the " Geology and Physical Geo- 

 graphy of Brazil," by C. F. Hartt (Triibner, 1870) ^which ap- 

 pears to be one of a series published under the title " Scientific 

 Eesults of a Journey in Brazil ; by Louis Agassiz and his Travel- 

 ling Companions"), the author describes a "sheet" of arena- 

 ceous clay, very uniform in composition, " absolutely structure- 

 less," " totally devoid of stratification," usually quite free 

 from pebbles or boulders. This sheet covers the coast pro- 

 vinces of Brazil from the level of recent estuarine formations — 

 even extending beneath these — to the tops of the highest hills 

 Mr. Hartt ascended. From his numerous topographical ob- 

 servations and his summary description of this superficial 

 formation, which varies in thickness from a few feet to 100ft., 

 I gather that it is a loess, and that it is pi'obably of similar 

 origin to the Timaru loess. The author and Agassiz could find 

 no ]node of deposition competent to account for all its features 

 save a general glaciation of the country. It was a boulder- 

 clay without boulders. The agency of dust-bearing w'inds, 

 however, was not one of those taken into consideration by 

 them. 



A superficial deposit in Lower La Plata, described by 

 Darwin (" Voyage of the ' Beagle ' ") as estuarine, " with con- 

 cretions and bones," may also well be a wind-drifted dust 

 formation. 



