618 



SCIENCE. 



FN. S. Vol. U. No. 45. 



(Zeitschr. Gesell. f. Erdk., Berlin, xxx., 

 1895, 1-94), with the following reflections, 

 here condensed: The most intimate knowl- 

 edge of the geology of a river basin, includ- 

 ing not only the composition of the strata 

 but even reaching to the origin of their 

 particles, is necessary to provide an inter- 

 pretation of the origin and continual changes 

 of a river S3'stem. Even in well-studied 

 regions the results do not suffice to solve 

 such problems, for unfortunately an in- 

 terest in these ' geographical ' questions is 

 often absent among geologists. On the 

 other hand, neither can the simple study of 

 the actual condition of a river course explain 

 the deeper problems of its geological de- 

 velopment. As in the organic world, so 

 here in the relations between mountain 

 form and river courses, only from a knowl- 

 edge of the processes of origin can we gain 

 a true understanding of the world as it 

 stands before our eyes (p. 92). This is 

 sound physiographical doctrine. Fiitterer 

 discovers from the small remnants of ancient 

 river deposits on the passes been the upper 

 Tagliamento and the streams of the Carin- 

 thian Alps that these modern rivers are only 

 feeble successors of a once much stronger 

 river system that headed in the central 

 Alps; and further that the Tagliamento, 

 which exceeds both in drainage area and 

 water volume the other rivers of the region, 

 is only a parvenu among the Carinthian 

 streams (91). The author notes (p. 78) a 

 close agreement of his results with those 

 obtained by Foerste in his thesis on the 

 Drainage of the Bernese Jura (Proc. Boston 

 Soc. Nat. Hist., 1892). Details are given 

 concerning many streams, after which a 

 general history of their development is pre- 

 sented (p. 76). 



A SWISS LANDSLIDE IN THE GLACIAL PERIOD. 



The valley of the Linth is obstructed for 

 about four miles above (south of) the vil- 

 lage of Glarus by a mass of loose material 



which Heim identifies as the product of an 

 immense landslide or mountain fall (Der 

 diluviale Bergsturz von Glarnisch-Guppen, 

 Viertelj 'schr. Naturf. Gesell. Zurich, xl, 

 1895, 1-32). The scar left by the fall is 

 traceable on the lofty slope about two miles 

 to the west. Morainic material lies upon 

 the slide, and hence it is regarded as of at 

 least glacial antiquity. Glacial action, 

 however, not only did not suffice to clean 

 out the valley, it did not even smooth 

 down the rolling surface of the slide, or 

 scrape away the river deposits that were 

 accumulated up-stream from the barrier. 

 The Linth now trenches the slide about half 

 a mile back from its front on the eastern 

 side of the original valley, as if the impetus 

 of the slide had raised its margin to an up- 

 hill slope. The greatest thickness of the 

 slide is 200 meters. Its original volume is 

 estimated at | km.^, or about eighty times 

 that of the great landslide of Elm in 1881. 

 The Linth has now carried away about \ 

 km.^; 4,000 or 5,000 years being thought 

 time enough for this work. 



VALLEYS IN THE PLATEAU OF THE ARDENNES. 



Arctowski describes this interesting re- 

 gion (Bull. Soc. geol. France, xxiii., 1895, 

 3-9) as the result of marine denudation of 

 a vigorous ancient mountain system, the 

 Cretaceous sea being regarded as the most 

 active agent in accomplishing its reduction 

 to baselevel. Following a miocene eleva- 

 tion of the region, streams began to sink 

 their valleys beneath its even and gently 

 sloping surface. The Hoyou, a branch of 

 the Meuse from the north, and one of the 

 most characteristic of the smaller streams 

 of the Ardennes, exhibits several alterna- 

 tions between gentler and steeper slopes, 

 although the points of increasing slope do 

 not manifest anj' definite relation to the en- 

 trance of side bi'anches or to the geological 

 structure of the bed. Arctowski therefore 

 concludes that the changes of slope indicate 



