Yol. 50.] SNOWDBIFT DEPOSITS DISCUSSION. 487 



blown dust deposit, though it passed into deposits which had been 

 re-arranged by water. Part of this lay at altitudes where snow fell 

 each year, but it was equally well and typically developed below 

 the level at which snow usually fell, aud where it was not preceded 

 by a long frost nor lasted long enough to form extensive drifts. He 

 did not think that the true loess could originate from the solid 

 matter left by melting snow, and it could certainly be formed without 

 the aid of snow. 



Dr. W. F. Hume observed that the views as to loess which still 

 held the field were three : — 



1. The diluvial theory, accounting for it as due to flood-waters set 

 in motion by volcanic action. This view appeared to be untenable, 

 if the total absence of volcanic evidence in the main areas where 

 loess was present were taken into account. 



2. The origin of the European loess as the result of the melting 

 of large glaciers, having been either originally deposited in lakes 

 or as fluviatile loam. This view was strongly held by many 

 Prussian geologists, aaolian action being almost entirely ignored. 



3. iEoHan action the prime factor, as maintained by Baron Ferd. 

 von Piichthofen, though glacial action might have played a con- 

 siderable part in originating one type of this deposit. Some deposits, 

 as in Australia and India, would appear to be entirely due to this 

 action. 



The suggestion made by Mr. Davison would be a subsidiary 

 aspect of theory No. 2. 



The Peesident drew attention to an important paper published 

 in the ' Geological Magazine ' for 1889 on the Origin of the Loess 

 (' Subaerial Deposits of the Arid Eegion of North America,' by Israel 

 C. Russell, of the U.S. Geol. Survey, "Washington, D.C., U.S.A., 

 Geol. Mag. dec. iii. vol. vi. pp. 289-295 & 342-350), showing 

 how a large portion of that deposit may have originated by fine 

 sediments deposited subaqueously in great, shallow, inland lakes. 

 The lakes having become desiccated, these sediments have subse- 

 quently been removed and re-deposited by aeolian action as unstra- 

 tified loess. 



