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Ročník:

56/2019

Název česky:

Zalednění Vlčího dolu v Krkonoších a ochrana jeho glaciálních tvarů

Název anglicky:

Glaciation of the Vlčí důl valley in the Krkonoše Mts and protection of its glacial landforms

Autor (autoři):

Vlastimil Pilous

Klíčová slova česky:

kar, stupňovitý kar, moréna, anemo-orografi cké systémy, antropogenní formy reliéfu, ochrana přírody

Klíčová slova anglicky:

cirque, cirque stairways, morains, anemo-orographic systems, anthropogenic landforms, protection of nature

Od strany:

119

Do strany:

144

Abstrakt česky:

Kar Vlčí jámy i morénový systém Vlčího dolu patří k nejzajímavějším krkonošským glaciálním formám,
ale navzdory tomu byla jejich výzkumu věnovaná ve srovnání s jinými lokalitami dosud jen velmi malá pozornost.
Proto má jejich poznání dodnes velké nedostatky jako celek a řada jednotlivých glaciálních tvarů zůstávala téměř
neznámá. Zdejší ledovec byl navíc výjimečný i tím, že se nalézal v poloze nejvíce vzdálené od nejsilněji zaledněných
Krkonošských hřbetů a současně i v nejmenší nadmořské výšce. To má své specifi cké důvody, avšak ani vysvětlení
této výjimečné skutečnosti nebyla dosud věnovaná pozornost, kterou by si zasluhovala. Nízká poloha zdejších
ledovcových forem má však i jeden mimořádně negativní dopad, neboť se nacházejí na okraji intravilánu Pece
p. Sněžkou a velká část dokonce přímo v areálech zimní sportovní infrastruktury této obce. Proto byly již v minulosti
zčásti zničené nebo v různé míře narušené. K prvním škodám došlo již v důsledku zakládání historických agrárních
a sídelních tvarů, ale zvláště pak v souvislosti masivním nástupem zimních sportů v poválečném období, s nímž je
spojené zřizování sjezdovek a jejich přístupových komunikací, lanovek, vleků i ubytovacích kapacit. Tlak na další
rozšiřování těchto aktivit trvá i v současnosti a dostává se do přímého konfl iktu se zájmy ochrany přírody, neboť
představuje přímé ohrožení glaciálních forem. Vlčímu dolu je proto v tomto směru potřeba věnovat zcela mimořádnou
pozornost a zásadním způsobem omezovat nebo i přímo eliminovat zde jakékoliv aktivity vedoucí k dalšímu
poničení nebo dokonce likvidaci zdejších glaciálních forem.

Abstrakt anglicky:

Vlčí jáma cirque and the moraine system of the Vlčí důl valley are among the most interesting glacial
landforms of the Krkonoše Mts (the Giant Mts), but despite this, they have so far received little attention compared
to other localities. Therefore, there are large knowledge gaps and many individual partial glacial imprints remained
almost unknown. The local glacier was also exceptional in that it was located at a position furthest from the most
intensely glaciated ridges of the mountain range and it is also located at the lowest altitude. There must be specifi c
reasons for this, but no justifi cation for this exceptional fact has yet received the attention it deserves. The location
and low altitude infl uenced the local glacial landforms negatively as they are located within the marginal part of the
Pec pod Sněžkou urban area. Moreover, signifi cant area is covered by the winter sport infrastructure. Local glacial
landforms were destroyed or damaged in the past, at fi rst by historical agrarian and residential impact, and especially
later in connection with the massive progress of winter sports in the post-war period, which involved the establishment
of ski slopes and their access roads, cable cars, ski lifts and accommodation facilities. The pressure to further
expand these activities continues even today and comes into direct confl ict with nature conservation concerns as
it poses a direct threat to glacial landforms. It is therefore necessary to pay extraordinary attention to the Vlčí jáma
cirque in this respect and not to allow any activities leading to further destruction or even liquidation of the local glacial
landforms.

Souhrn anglicky:

Although glaciation of the Vlčí jáma cirque has been
known since the very beginning of studies of glacial
forms in the Krkonoše Mountains, and despite the
local well-developed moraines, geomorphologists
remained only marginally interested in it as they
focused mainly on the largest glacial landforms in the
higher-elevated parts of the mountain range. In addition,
some of the relatively small pieces of information
that have been published about the Vlčí jáma cirque
are questionable and others can even be excluded.
Detailed fi eld research has enabled the local glacial
and related erosional processes to be refi ned and evaluated
in more detail. A previously known fact, that the
Vlčí jáma cirque is situated at the lowest elevation, but
at the same time has one of the most well-developed
morphology has been further refi ned. It was unambiguously
confi rmed that it is a stepped cirque, divided
even by two steps one above the other. In comparison
with the only other cirque stairway of the Krkonoše
Mts, the Úpská jáma cirque, the steps are better
developed as they are present along the whole width
of the cirque. This is caused by the bedrock, which
is formed of the phyllites of the Krkonoše crystalline
complex. The Vlčí jáma cirque is the only one of the well-developed cirques in the mountain range having
this lithology. Therefore, the infl uence of a passive
morphostructure in the form of alternating strips
of differently resistant chloritic-sericitic and graphite-
seritic phyllites intersecting the whole cirque was
signifi cant. Specifi c features of the Vlčí jáma cirque,
which can not be found in any other Krkonoše Mts
cirques, are a small forest and partly sloping peat
bogs, whose formation was strongly affected by the
steps of the cirque.
An extraordinary feature is the combination of the
cirque with the closely adjacent, markedly eroded
ravine of the Temná bystřina stream with landslides,
which continues as a braided stream at the bottom of
the cirque, where both glacial and colluvial material
were deposited.
Laser scanning images unequivocally confi rmed
Partsch's original claim that the terminal moraine of
the Vlčí důl valley is the best-developed moraine in the
Krkonoše Mts, which was later questioned by some
authors, who attributed it only to a polygenetic origin.
Also, a detailed fi eld survey has shown that this
polygenetic origin can be unequivocally excluded. It
was clearly proved that Holocene erosion and accumulation
processes of the side streams leading to the
Vlčí potok stream had only a minimum role in their
appearance of the moraines, which is manifested by
their hanging termination. On the contrary, the arc of
the terminal moraine was eroded by the greater water
fl ow in the Vlčí potok stream, which cut through a wide
rift to the ongoing valley. On the right side, however,
the relict of the terminal moraine has been preserved
in the form of a distinct arcuate ridge, which is very
well-developed and valuable landform.
A specifi c feature of the Vlčí důl valley, both of the
cirque itself and the moraines in particular, is the frequent
presence of large glacial boulders whose longer
axes range from 3–7 m. Their importance lies, inter
alia, in the fact that they allow to estimate the position
of trimline even in an area where there are no clearly
identifiable moraines. Such a large proportion of
the boulders can be attributed to crystalline rocks in
the bedrock of the rock outcrops on the cirque steps,
which were eroded and further transported by the
movement of the glacier. Some of the blocks located
directly at the bottom of the steps indicate that the
process of degradation continued through congelifraction
even in the Holocene. The low elevation of
the cirque led in the Krkonoše conditions to a unique
phenomenon, that consists of enclave-type settlement,
including accompanying agrarian landforms,
as well as artifi cial hydrographic changes (diagonal
canals and slope reservoir, redirection of some fl ow
sections) directly in the cirque area.
The post-war era was connected with the development
of tourism and especially sporting activities in
the area of Pec pod Sněžkou. The establishment of
ski slopes, access roads and parking lots, as well as
the construction and expansion of accommodation
facilities, caused serious damage or even destruction
of some of the glacial landforms in the Vlčí důl valley.
The work lists the damage that has occurred so
far and is also a fundamental resource for the work of
conservationists. Due to the proximity of urban areas
and sports facilities, pressure for the construction and
expansion of various buildings in this area is continuing
at present. It must be clearly stated that no further
interventions into the original glacial landforms
of this extremely valuable location can be allowed.

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