Dr. Sandherger — The Upper Rhine Valley. 219 



have not yielded any Yortebrata nor sliells ; and there is also a gap 

 between the Eppelsheim Fauna and that of the Middle Diluvial 

 epoch not yet filled up. 



When and how the dam in the Upper Ehine valley by Schaff- 

 •hausen and Freiburg was destroyed, and how the river found a 

 free course to the north, this is neither the time nor the place to 

 decide; this however is certain, the remodelling of the present 

 river-bed must have required an extraordinarily long time, and indeed 

 was already in existence at the commencement of the Glacial epoch. 

 Along almost the whole line from Basel to Bonn we meet, at a 

 height ranging up to 150 metres above the present river, an old 

 river-bed, which stretches, according to the contour of the land on 

 either side, from three to six miles inland to the hill boundaries, 

 which then formed the river-bank, and is still easily recognized as 

 liver-terraces. The lower bed consists of pebbles and sand, on 

 which lies Hill-loess, In the present river-valley, but at a much 

 less height above the present water-level, we again find gravel, 

 often more than thirty metres thick, and Valley-loess. In this w© 

 first find, here and there, interstratified thin brown coal-beds, as, 

 for example, at Steinbach near Baden-Baden, analogous to the beds 

 at Utznach and Diirnten in Switzerland, and Imberg near Sont- 

 hofen in Bavaria. As far down as Heidelberg the gravel still 

 contains Alpine pebbles and rolled moraine rubbish from the 

 gigantic glaciers of the Ehine, as I have mentioned elsewhere. That 

 the river must have required a very long time to cut out its channel 

 to the lower gravel-bed, now forty metres above its present level, 

 in addition to the 110 metres of the 150 metre-level mentioned 

 above, requires no further explanation. It had, however, to dis- 

 pose of ah extra bulk of water in certain seasons, as it does now — 

 a point to which I will return later. 



This hypothesis of a long lapse of time agrees not only with 

 the mechanical modelling work of the river, but also with the totally 

 different character of the Fauna at the beginning and the end of the 

 period, which I shall proceed to show immediately. 



In the Ehine valley the larger Vertebrata are found, as in other 

 river valleys, chiefly in bays formed by the debouchment of side- 

 valleys into the chief one, as for example at Istein. 



With regard to this latter view, the old Main delta, in the imme- 

 diate neighbourhood of Hochheim, and from thence as far as Walluf, 

 is known as the most celebrated and fertile finding-place for Diluvial 

 Tertebrata on the whole Ehine, and in the sandpits by Mosbach 

 near Biebrich, and also at Schierstein, they are exceedingly numer- 

 ous. The pebbles form a veritable pattern card of all the rocks 

 of the Main district. Along with the Sericit shale and Quartzite of 

 the Taunus, and the Tertiary stones and Basalts of the neighbour- 

 hood of Frankfort, are found the Muschelkalk of the Kinzegthal 

 and Bunter sandstone of the same district. Hornblende and Gneiss 

 from Aschaffenburg, and, indeed, even the almost indestructible 

 siliceous shale from the upper Main in the Fichtelgebirge, are not 

 wanting. The coarser gravels contain the larger Yertebrata ; the 



