GROLOGY — WILLIS. 197 



PHYSIOGRAPHIC NOTES. 



Central Germany and Northwestern Austria. — The mountains of 

 central Germany, from the Rhine eastward, and of Austria north and 

 west of the Vienna basin, exhibit in general an even summit surface, 

 in which valleys are more or less developed. Penck has shown that 

 this surface is a peneplain of Cretaceous age, and that the valleys 

 have had a complex history involving erosion, submergence, filling, 

 uplift, and re-erosion, during and since the middle Tertiary. 



To become familiar with this type of mountains, I made observa- 

 tions along the Rhine, across the Thuringer Wald, along the Elbe 

 above Dresden, on the Danube above Vienna, and in northeastern 

 Bohemia near Zwittau. In the last two districts I accompanied Pro- 

 fessor Penck and his students. 



The interpretation worked out by Penck was verified and to some 

 extent supplemented by the observation that the peneplain was not 

 only uplifted, but also warped. Near Dresden it was seen sloping 

 from the upwarp of the Erzgebirge down to and beneath the down- 

 warp of the plains of northern Germany; and near Krems, on the 

 Danube, a similar relation was noted with reference to the Vienna 

 basin and the mountains northwest of it. In Bohemia the combined 

 geologic and physiographic evidence shows that warping occurred 

 before or during the Miocene, and in later Tertiary was followed by 

 other warping movements, differing in direction and position from the 

 earlier ones. And on the Elbe, in the district known as the Saxon 

 Switzerland, the valley historj'- consists of two episodes, one of late 

 Tertiary date, the other Quaternary, showing that warping has there 

 continued in notable degree to relatively recent times. 



As the latest folding suffered by rocks of this general region was 

 that at the close of the Paleozoic, the relation between folding and 

 warping is very remote, if indeed any genetic relation exists at all. 



Karpathians in Western Galicia. — Accompanied by Professor Uhlig, 

 I visited the mountains of Oligocene, Eocene, and older strata, south 

 of Neu-Sandec. The particular locality was chosen because of the 

 occurrence of estuarine Miocene near that place, in a wide but deep 

 valle}', opening northward toward the plains of Russia, and of the 

 critical relation of the Dunajec River to the structure, which it crosses 

 at right angles. 



The latest episode of folding in this region affects Oligocene strata, 

 and the elevation of the mountain range has hitherto been correlated 

 with it. There are, however, physiographic evidences of a more com- 

 plex sequence of events, which we noted and in regard to which we 



