ERRATIC BLOCKS. 183 



ever, are in the Alps ; and in many cases the path may be traced 

 that they have followed from there into the low grounds by 

 the blocks and debris belonging to the same mountains along its 

 course. Thus near Katzenriitihof, on the Katzensee, a block 

 is found consisting of a very peculiar variety of granite, such as 

 occurs nowhere in the whole Alpine region, except at Pontel- 

 jestobel, above Trons, in the Canton of the Orisons. 



Blocks of the same granite are scattered over the range of 

 hills on the right bank of the Lake of Zurich, and in the district 

 lying further to the east, as, for instance, in the Gaster, in the 

 valley of Wallenstadt, and in innumerable quantities from 

 Sargans to Ragatz, and on the left side of the Rhine up to 

 Trons. The same granite blocks may be traced from Sargans 

 and through the lower Rhine valley as far as Rorschach. All 

 these blocks lie upon the left side of the Rhine ; and it is remark- 

 able that not a single fragment occurs on the right bank. The 

 innumerable blocks of sernifite (red acrestone) which are scattered 

 over the Canton of Zurich no doubt originated in the sernifite 

 mountains adjacent to the basins of the Linth and of the Wallen- 

 see. As several varieties of sernifite occur in that region, there 

 are many cases in which the mountain masses may be ascertained 

 from which the blocks probably took their origin. Thus the 

 rock of the enormous " ploughstone/' above the parish of 

 Erlenbach in the Canton of Zurich, agrees perfectly with the 

 fine-grained porphyroid sernifite of the Gantstock in the middle 

 of the Canton of Glaris, and probably came thence ; indeed 

 this mountain mass is still surrounded by innumerable vast 

 rocky fragments, and has received its name from this circum- 

 stance. 



In the basin of the Reuss are found immense numbers of 

 blocks of gneiss and gneissic granites from the St. Gothard. 

 They may be observed on the west side of the range of the Albis 

 and Uetliberg ; and near the Schnabelpass, in the gorge of the 

 Albis ridge, some granites have been transported to the eastern 

 side, while still more have traversed the hollow ravine of the 

 Mutschelle between the Uetliberg and Hasenberg, and pene- 

 trated into the valley of the Limmat. On the other hand a few 

 blocks of sernifite have been removed from the basin of the 

 Limmat into that of the Reuss. 



