270 I \ V I/.n NEW YORK ACADEMY OF SCIENCES 



utmost importance both in Europe and America in the correlation of 

 human and mammalian life, also in their significance as to the climate 

 of iiiterglacial times. Loess consists of a fine, porous, silicious, calcareous 

 silt, usually of light brown color, characterized by a peculiar competency 

 to stand in vertical walls during erosion. Its origin and transportation 

 are believed to have been partly sub-glacial, partly fluviatile, partly seolian. 

 The fine mud carried by the sub-glacial streams in glacial times became 

 desiccated and redistributed by the wind. Penck (1904) describes the 

 Pleistocene loess as formed in districts traversed periodically by great 

 streams leaving dry mud which in arid periods was redistributed by 

 seolian agencies. Its Pleistocene distribution is quite independent of alti- 

 tude since it occurs in the interglacial deposits of Europe from sea level 

 to a height of 1,500m. 



CLIMATE 



A considerable part of the elevation of the Swiss Alps apparently took 

 place (Penck, 1910) during the Second Interglacial Stage, and this in- 

 creased altitude is considered by some European authorities to be the 

 cause of the greater extent of the Third glaciation in the western Alps. 



The Hottinger breccia near Innsbruck is referred by Penck (1909, p. 

 1157) to the Second Interglacial Stage with its rich flora indicating a 

 climate warmer than that of present times; this breccia lies on one of the 

 old "High Terraces" of Second Interglacial times. The plants include 

 the fir (Pinus sylvestris) , spruce (Picea sp.), maple (Acer pseudopla- 

 tanus), buckthorn (Rhamnus frangula), several willows (Salix nigricans, 

 S. glabra, S. incana, 8. triandra), the wayfaring tree (Viburnum lan- 

 tana), yew (Taxus baccata), elm (Ulmus campestris) , straAvberry (Fra- 

 garia vesca), self-heal (Prunella vulgaris), beech (Fagus silvatica) , and 

 mountain ash (Sorbus aucwparia) , buckthorn (Rhamnus H Getting ensis), 

 related most closely to R. latifolia, now living in the Canary Isles, the 

 box (Buxus sempervirens) , also a southern species; and most important 

 of all a rhododendron (R. ponticum) which now lives in the Caucasus 

 five degrees south of the latitude of Innsbruck and in a climate on the 

 average 3° C. warmer. Taking all the facts into consideration Penck 

 concludes that the climate of Innsbruck in the days of the Hotting brec- 

 cia was 2° C. higher than it is now. In correspondence with this the 

 snow-line stood 1,000 ft. above its present level, and the Alps save for the 

 higher peaks were almost completely denuded of ice and snow. 55 



A picture of the flora of the Second long warm Interglacial Stage is 

 also afforded in the Quaternary tuffs of Provence, where the remains of 



55 Sollas, W. J. : AucieDt Hunters and their Modern Representatives, p. 27. 8vo. 

 MacMillan & Co. London, 1911. 



