| During the 100-year-long history of scientifi c research
on the inanimate nature of the Krkonoše Mts (the
Giant Mts), most attention and work has been focused
on glacial and related nivation processes and landforms.
Still new and past findings show that this
research is far from over. In recent decades, we have
witnessed studies focused almost exclusively on sites
of large Pleistocene glaciers (ie on the Czech side of
the mountains – cirque and valley glaciers). On the
contrary, many other localities have been almost or
completely neglected, and therefore we know very little
about them, although some have interesting specifi
c features and differences. However, focusing only
on individual localities delays the evaluation of the
overall character and the spread of glacial and nivation
processes and their relief forms throughout the
mountain range. The maps produced by aerial laser scanning have
been an important aid in this case, showing that the
landforms of improved protocirques and shallower
nivation hollows were created by the favorable interplay
of circumstances even in lower, parts of the mountain
range, which until now have remained hidden
and unknown due to high forest cover. Their position
is strongly related to the leeward parts of the socalled
anemo-orographic (A-O) systems, which are
extremly important in the Krkonoše Mts, but probably
even on global scale. The orientation of structular
landforms and subsequent valleys corresponds
with the prevailing wind direction. The importance
of wind for the formation of these forms is generally
known, but it is only generally presented, without
evaluation of its effect on particular forms, especially
outside the peaks of the mountain range. We
can see from a number of glacial-nivation forms of
the lower elevation that, if its favourable leeward
position meets a suffi ciently large defl ation surface,
relatively developed holows in surprisingly low positions
can arise. Moreover, the landforms in the lower
parts of the mountain range show that not only planation
surfaces are often used as a defl ation surface,
but also large and shallow slopes having a convenient
orientation in terms of wind fl ow play important
role. In such a case, not only vertical but also horizontal
wind turbulence can occur in the leeward protocirques
and nivation hollows. Moreover, these hollows
in the montane stage do not only arise in valley
heads, as previously and uncritically stated, but even
more often in a lateral valley slope position.
The role of the Černohorská rozsocha ridge, which
is the only one having a diagonal direction towards
the main Krkonoše ridges and thus consequent the
valleys of the main rivers, is extremely interesting, but
still completely neglected. The ridge caused a local
diversion of the A-O systems wind fl ow of (most notably
in the area of the high western slopes of the Liščí
hora Mt.), which resulted in the creation of several protocirques
and nivation hollows, but especially the lowest
cirque of the Krkonoše Mts – the Vlčí jáma cirque.
Furthermore, assessment of the combined A-O system
and the necessary minimum defl ation surface area
implies that the two large long valleys (Mumlavský and
Dlouhý důl valleys) were not glaciated as a whole. An
insignifi cant exception is the minor glaciation in the
uppermost part of the údolí Bílé Labe valley, thanks to
its high altitude, combined with exceptionally favourable
surface conditions with a vicinity to the gently
sloping surface of the Bílá louka etchplain, possibly
covered by fjeld glacier. Similarly, some other valleys
were not glaciated, for example, the Modrý důl
valley with only narrow ridges rising above the valley
closure, creating no signifi cant defl ation surface.
Glaciation of the Krkonoše Mts is often associated
with the proximity of the continental ice sheet, presumably
making it more extensive. However, there is
a possibility of a counterproductive variant, in which
the desiccating catabathic winds blowing from the
Nordic glacier intensifi ed the relatively continental climate
of the area. Compared to the western Hercynian
mountains, which were lower, further from the iceshield,
but incomparably more glaciated, this would
have had a negative effect on the extent of glaciation.
The question of the emergence of the Sněžka Karling,
which was not surrounded by glaciers during
the last Würm glaciation by glaciers from all three
sides, as is traditionally thought, but only from two,
is also open. Possibly, it could have been surrounded
and modelled by valley glaciers from all three sides
during some earlier glacial phase with more extensive
glacial extent. |