Structure of the Eastern Alps. 405 



entire skeletons of the Mammoth. Such a deposit ill represents the rapid 

 operation of a retiring- flood. 



It is greatly expanded near Krenis and St. Piilten ; reaching occasionally the 

 thickness of 140 feet^ and having, near tiiose places, tlie exact appearance of 

 the old alluvial hillocks in the valley of the Rhine, which have been described 

 by M. Voltz. 



Unconformable masses of conglomerate appear (as has been already stated) 

 in several places on the north ilanks of the Alps* — apparently produced soon 

 after the last great movements of elevation^ which set on edge all the neigh- 

 bouring strata. We do not however venture rigidly to conijmre the horizontal 

 conglomerates of Salzburg and Bavaria with any of the upper formations in 

 the basins of Vienna and Styria ; where, as we have seen, all the tertiary groups 

 are nearly horizontal, and where there does not appear to have been any break 

 of continuity between the oldest and youngest of the successive deposits. 



To the N.W. of the Wiener-wald appears a similar phenomenon to that 

 already described at Ortenberg (p. 380) : the deposits in this part of the valley 

 of the Danube have, in common with all those on the Ilanks of the Bohemian 

 chain, escaped the influence of the last movements which dislocated the newest 

 strata on the flanks of the Bavarian Alps. For instance^ in several places 

 near the right bank of the Danube (and especially on the banks of the Pielach, 

 just above its confluence with that river at Miilk), are thick stratified masses 

 of marl and sand resembling the Tegel and other beds of the Vienna basin, 

 resting horizontally on inclined strata of gneiss and mica-schistf . One of these 

 masses of horizontal, blue marl contains a bed of lignite (too poor to remunerate 

 those who have attempted to work it) ; and many fossil shells, out of which we 

 collected several species of Ostrea, all we believe undescribed, but one re- 

 sembling Ostrea jiaheLlula (Lam.); a Cardium; aNerita; three species of Ce- 

 rithium; and several very minute, undescribed bivalves. The lignite, where it 

 has been worked, is about 200 feet above the level of the river ; and in general 

 the system of blue marls, in the little valley of the Pielach, is surmounted by 

 thick beds of yellowish sand without fossils. We have not materials sufficient to 

 define the comparative age of this deposit : but it is obviously much more 

 analogous to the lignites in the Styrian basin, than to any of the formations on 

 the north flank of the Alps described in the preceding chapter. 



Lastly, we may notice the structure of the tertiary hills, surrounding the 

 alluvial basin of St. Polten, on the road from Miilk to Vienna. They are 



* Plate XXXVI. fig. 6 and 9. f The convent of Molk stands upon the 



primary strata, which occupy the banks both of the Danube and the Pielach. 



