248 Dr. A. P. Young—Glaciation of Navis Valley. 
This form of disruption without transportation finds a striking 
illustration in the Gross Kaserer, 3270 metres, a subordinate summit 
of the Olperer group. This peak is now and probably has during 
Interglacial periods always been above the snow-line. The great 
crevasses which form between firn and glacier-ice are well developed 
some way below the summit. The appearance presented is that of 
a pile of big boulders; the standing rock is not seen. The massive 
rocks of the Olperer gneissic series break up into blocks too large to 
be disturbed by the movement of the firn. ‘The mound, moreover, 
stands out above the firn and has no permanent covering of snow. 
This mode of disintegration is not confined to glaciated tracts, and 
good examples of disruption with little movement are to be found on 
ancient land surfaces, such as the Indian Peninsula and parts of 
South Africa. In the Alps the ‘Block-meere’ or block-wastes are 
frequent in high ground; most of them were no doubt accumulated 
when the snow-line stood for a time at a corresponding level. 
Kroston 'o-pay In Hiew Grovunp. 
The effects of erosion hitherto treated belong as regards the Tarntal 
mass to past history, and are referred to conditions of clhmate other 
than those at present here prevailing. As already shown,’ the 
climatic snow-line is still, in all probability, below the highest 
summits, and it is instructive to watch the forms of atmospheric 
activity of to-day. 
The serpentine blocks above 2600 metres are covered with wart-like 
prominences a centimetre or so in diameter; these warts are found 
occasionally on standing rock nearly up to the summits. They are 
due to the rapid weathering of the serpentine round the more resistant 
bastites which form the projecting parts. The prominences are seen 
on blocks below 2600 metres; at the lower levels, however, they are 
much worn down and do not seem to be forming afresh. The chief 
agent in this form of weathering is the nearly pure water trickling 
from the melting snow which covers the ground for a considerable 
part of the year. 
An instance of the same kind of work is furnished by the well- 
known ‘Karren’. ‘This form of sculpture is peculiar to calcareous 
rocks; straight grooves resembling the ruts of cart-wheels are crowded 
together in parallel series and often cover wide areas, the ‘ Karren- 
felder’.? The ruts are determined by structures in the limestone, 
thin bands, bedding-planes, joints; they were no doubt formed under 
snow, when the snow-line stood at a corresponding level, and are due 
to the solvent action of nearly pure water. The ‘Karren’ are only 
found at high levels; they may be expected to furnish useful 
information concerning former stands of the snow-line. 
A steep slope on the south side of the saddle between Reckner and 
Little Reckner is covered to a depth of several feet with an incoherent 
deposit of more or less finely divided serpentine almost free from 
1 See Grotocicat Macazinz, August, 1909, p. 346. 
2 Only the simplest form is here described. For details and figures see Max Eckert, 
‘Das Gottesacker, ein Karrenfeld im Allgiiu’’: Wiss. Erginzungsheft zur Zeitschrift 
der D. und O. Alpenverein. 
