Januaby 5, 1900.] 



SCIENGE. 



35 



the maia and the tributary channels becomes 

 very striking, while we lose sight of the accord- 

 ance that must have prevailed in the confluent 



surfaces of the main glacier and its tributaries. 

 The river channel as well as the glacial chan- 

 nel is U-shaped, but the abandoned glacial 

 channel is so large that it often gives name to 

 the valley in whose bottom it is eroded. The 

 accompanying diagram roughly presents the 

 form of an Alpine valley in preglacial (back- 

 ground), glacial (middleground), and postgla- 

 cial (foreground) time. 



The heavy glaciation of valleys eroded in the 

 massive gabbros of Skye has produced the fol- 

 lowing features, as noted by Harker (Geol. 

 Mag., London, 1899, 196-'99). The cross-sec- 

 tion of the valleys is U-shaped, especially in 

 their upper part. The head of the valley ex- 

 pands in a corrie (cirque or amphitheatre) 

 whose floor is often a rock-basin holding a tarn. 

 In longitudinal profilCj the floor of a valley 

 often consists of two or three stretches of rela- 

 tively gentle slope (or even of basin-form) sepa- 

 rated by relatively sudden descents. Tributary 

 valleys mouth at a considerably higher level 

 than the floor of the main valley. McGee's 

 paper on 'Glacial Canons' {Journ. Geol., II., 

 1894, 350-364), referred to by Harker, may be 

 read to advantage in this connection. 



It is noteworthy that the discordance of side 

 and main valleys, emphasized by Penck as a 

 characteristic of glacial action, and clearly 

 recognized by McGee and Harker, has been 

 mentioned in but few essays on glacial erosion ; 

 yet it can hardly be doubted that such discord- 

 ance is one of the most striking features of 

 strongly glaciated mountain regions. 



ANCIENT VALLEYS OF NORTHEASTEEN 

 GERMANY. 



The origin of many broad valleys in north- 

 eastern Germany, as determined by ancient riv- 

 ers flowing westward, marginal to the retreating 

 ice-sheet of the last glacial period, has lately been 

 restated by Keilhac (Verh. Oesellsch. Erdlc, 

 Berlin, XXVI., 1899, 129-139, map), with fuller 

 detail than was given in the earlier explanations 

 by Berendt and Girard. Five important valley 

 courses are traced, exterior to five morainic 

 belts ; the southernmost connects the Oder at 

 Breslau with the Elbe above Magdeburg ; the 

 northernmost led the Oder from Stettin north- 

 west to Ribuitz and south again from Liibeck 

 to the Elbe at Laueuburg. Lakes are indicated 

 by horizontal shore-terraces at certain depressed 

 areas along the valley courses, where the pres- 

 ent northward discharge was ice-barred. The 

 ancient ice-margin valleys owe their consider- 

 able breadth to the large volume of the rivers 

 that were then supplied by melting ice on the 

 north as well as by rainfall on the south. The 

 rivers of to-day follow the ancient marginal 

 valleys for moderate distances only, and then 

 turn northward through depressions that were 

 opened to them as the ice melted back ; some- 

 times again turning westward for a stretch 

 along the next marginal valley that is encount- 

 ered. Thus sub-rectangular bends to the right 

 and the left are systematically repeated seven 

 times by the Oder, between Breslau and Stettin. 

 W. M. Davis. 



ZOOLOGICAL NOTES. 



Mr. C. W. Andrews, in a recently issued 

 part (Vol. XV., part 3), of the Transactions of 

 the Zoological Society of London, describes at 

 length and figures the skull and portions of the 

 skeleton of Phororhacos inflcdus, one of the 

 gigantic extinct Patagonian birds. In discussing 

 the relationship of the genus, which is put 

 among the Oruiformes, Mr. Andrews shows a 

 decided leaning toward Cariatna, saying that the 

 relations of the one toward the other are much 

 the'same as those of the extinct Glypiodon and 

 Panocthus towards existing armadillos. Mr. 

 Andrews will be glad to know that among the 

 material obtained for Princeton University by 



