Dr. A. P. Young—Gtaciation of Navis Valley. 251 
The highest level reached by these gneiss blocks cannot therefore be 
precisely known. But the valleys of the Klamm and Weidereich 
brooks which join to form the Navis are hardly accessible enough from 
the inhabited parts to have been exploited by cottagers in search of 
stone, and it is unlikely that the Sill erratics were carried much above 
the level of Navis even during the period of extreme glaciation: to 
which their transport is to be referred. 
In the Klamm Valley, just above Navis at about 1400 metres, is 
a conspicuous bar of moraine material, so little above the point reached 
by the crystalline erratics that it may well mark the site at which the 
Klamm Valley glacier was met by the back-flow of the Sill ice. It is, 
however, more likely that this is the end moraine which was formed 
by the Tarntal ice-tongue during a retreating stage of the Wirm, 
at which time it may be supposed that the Sill ice was also in retreat. 
In either case the ice-surface could not have stood much higher than 
1500 metres. The valley drift which in a measure determines cereal 
cultivation does not reach above 1600 metres, and may belong in part 
to an older glaciation. 
In one part of the Navis Valley, on the north side near the Wetter- 
kreuz at 2151 metres, there is a marked change in the surface gradient, 
the slope being much steeper below the Wetterkreuz than above it. 
If this ledge is the rim of an ice-trough it most likely belongs to one 
of the earlier glaciations, when the floor of the valley and the snow- 
line were both higher than they were during the latest, the Wurm 
glaciation. But the gently sloping floor above the Wetterkreuz may 
be accounted for as a plain of nival denudation, the ‘ Abtragungsebene 
der Schneegrenze’ of Richter.!| The masses of moraine material above 
2200 metres which accumulated during the persistence of the 2400 
metre snow-line make this explanation the more acceptable. Taking 
all the evidence together, it appears most improbable that the ice- 
surface was at 2100 metres when the Schafseiten corries were last 
occupied by ice, or even when they were first formed, supposing them 
to have been more than once filled with ice. 
Of the four resting-stages which have left their traces in the 
Tarntal district two may be doubtfully correlated with Glacial periods 
recognized elsewhere. 
The bar or ‘ Riegel’ at 1400 metres in the Klammbach may be the 
equivalent of the moraine deposits above Trins in the Gschnitztal, the 
‘Gschnitzstadium ’ or , stage of Penck. The Trins glacier rising in 
the high ground of the Stubaital Alps would naturally end at a lower 
level than the glacier of the same date in the Navis Valley with 
a much smaller feeding-ground. It should, however, be noted that 
the terminal moraine of the y stage is placed by Penck at the mouth 
of the Navis Valley.?, The post-Wiirm snow-line of the Griibl at 
2400 metres would appear to be somewhat higher than that of the 
y stage of this valley, to which Penck assigns a level of 2100 metres. 
For the Gschnitztal the snow-line of the y stage is fixed at 2300. 
| E. Richter, ‘‘ Geomorphologische Studien in den Hoch-Alpen’’: Petermann’s 
Mittheilungen Ergdnzungsheft, 1900, vol. cxxxu, p. 77. 
2 Penck & Briickner, Die Alpen im Hiszeitalter, 1907-9, p. 343. 
