INFLUENCE OF STRATA UPON SCENERY. 
265 
Another reason which affects the landscape in 
districts of sedimentary and Crystalline rocks is that 
the former crumble away more rapidly, and thus 
more quickly lose the rounded surfaces due to ice 
action. Thus, as we ascend the valley of the Reuss, 
where we leave the softer strata and enter the dis- 
trict of Gneiss, we also commence a scenery of knolls 
rounded by ice. 
In calcareous districts “weather terraces” form a 
special feature (Figs. 44, 45 pp. 184,185). They are due 
to a succession of rocks of different hardness and tough- 
ness, so that some strata weather back more quickly 
and take a gentler slope than others. Crystalline 
rocks are generally more homogeneous, weather more 
evenly, and consequently present more regular and 
continuous slopes. The Bristenstock, for instance, 
which towers over the Reuss, is a beautiful example. 
For a height of 2 500 metres it presents an unbroken 
slope at an angle of 36°. Weather terraces are 
particularly conspicuous in certain lights, and especially 
in winter when there is snow on the gentler slopes. 
Even in summer, however, the contrast of vegeta- 
tion is often striking, some lines being marked out 
by luxuriant grass or bushes, while others are com- 
paratively bare. On Granite or Gneiss a good 
mountaineer can go almost anywhere, while in moun- 
