1854. J SCHLAGINTWEIT — BAVARIAN ALPS. 357 



the Ammer, which I have more especially examined. In those 

 localities where blocks of larger size appear in greater number, they 

 are sometimes more numerous, especially in the upper parts ; but 

 they are always imbedded between the other diluvial boulders, and 

 are in part rounded, and in part they have preserved fresh angles. 

 But it would be quite erroneous to suppose that these larger blocks 

 are necessarily only limited to the upper beds ; I have convinced 

 myself by repeated careful examinations that they also occur, though 

 generally less numerous, in the lower beds, and I have seen very 

 large blocks which have sometimes been brought up from consider- 

 able depths in the excavation of wells. 



The occurrence and the distribution of the erratic rocks on this 

 part of the Bavarian Alps, and plateau bordering them to the north, 

 seem evidently to show that here at least they must have been 

 transported, and deposited in the same mode and at the same time 

 as all the rest of the diluvial limestone and sandstone boulders 

 amongst which they lie, and which cover to so great an extent and 

 vnth so great a thickness the Bavarian plateau. 



I need scarcely add, that the facts and the remarks which I have 

 now brought forward relate only to that part of the Bavarian Alps 

 which forms the subject of this paper. The erratic and diluvial 

 phsenomena all around the Alps are so extended, and they present 

 such remarkable diiferences in various parts of this chain, that they 

 must, in my opinion, be studied minutely in different districts before 

 we can venture on general conclusions. But I may be allowed to 

 say, that, generally speaking, the erratic rocks which occur on the 

 plains all around the Alps have been too much regarded as merely 

 a superficial deposit ; and that, by examining different good sections, 

 erratic pebbles are found to descend more or less deeply into the 

 interior of the diluvial boulder beds. 



The occurrence and the distribution of the erratic blocks on the 

 extensive diluvial formations of the basin of the Lake of Constance, 

 are, according to the minute observations of Prof. Fromherz*, very 

 analogous to the phsenomena which I observed on the Bavarian 

 plateau. 



These very remarkable heaps of enormous and angular erratic 

 blocks principally occur in Switzerland and on the slopes of the Jura. 

 Every one who has studied the present physical conditions of glaciers, 

 and who has seen the great oscillations to which these ice-masses have 

 been often subjected, even in historical times, will perfectly agree, 

 that in former geological periods, — when the Alps were surrounded by 

 large masses of water, when there was a greater amount of moisture 

 in the atmosphere, and a greater quantity of snow-fall, — the glaciers 

 may very probably have undergone most considerable changes of 

 extension. The transport of debris from the central crystalline por- 

 tions of the Alps may have been in some places, as in the valleys of 

 the Rhone, of the Aai', of the Inn, &c., particularly favoured by that 

 greater extension of the glaciers. 



It is further very essential to recollect the importance of large 

 * Leonhard und Broim's Jahrbuchfiir Geognosie, IS.'iO, p. 641-G56. 



