ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

tion of particular types of landforms. Relief of the submarine
forefield of the glacier has been studied using sonar
sounding. Frontal part of the glacier can be divided into
three dynamic zones:
1. one zone of tension flow of ice stream ending down to
the sea in the calving cliff with high flow velocity and distinct
annual oscillations of the front position,
2. two zones of compression flow of the lateral part of the
glacier terminated on land with low velocities and slower
recession when compare to (1),
3. narrow transition zones between the both mentioned
above.
The compression flow zone (2) can be devided into two
subzones: (Za) where flow vectors are normal to the glacier
front and (Zb) where directions of vectors are oblique to
the glacier edge.
Submarine annual push moraines and contacts fans are associated
with slow winter advance and summer fast retreats
of the calving cliff in the tension flow zone. Humocky
moraine, characteristic for compression zone 2a
and enlongated ice-cored humocks with crests oriented parallely
to the glacier edge, represents zones of 2b. In narrow
transitional zones (3) one can note fluted moraine and
small annual moraines.
A model of sediment transfer and deposition rate in particular
dynamic zones is developed basing upon flow velocity
measurements and data on summer ablation near the
glacier front (including the ablation by calving as well).
GRZEGORZ JANICKI l & WOJCIECH ZGLOBICKI 2
The conditions of development of episodic channels in
loess areas of the Lublin Upland (SE Poland)
1Department of Physical Geography and Palaeogeography,
Urnes, 20-033 Lublin, Poland
2 Department of Geology, Urnes, 20-033 Lublin, Poland
Nowadays in the area of loess uplands of Central Europe
one can observe changes of conditions of functioning of
geomorphologic systems. These changes are a reaction of
the natural environment to human interference which
upsets the balance of nature. In particular, agricultural activity
which has lasted since the Neolithic Period contributed
to almost total degradation of natural flora (mixed and
deciduous forests) by giving considerable forest areas over
to agriculture. The lack of flora in transitional seasons
(spring, autumn) in agrocenosis of the temperate zone is
the reason why these terrains, which are occasionally called
«a cultural steppe», are modelled in a way similar to that
occurring in the regions of semi-arid and cold zones.
Poor flora or its total absence favours fast forming of outflows
and rapid surface flows of water, the energy of the
latter being considerable. This shows in a particularly distinctive
way during episodic phenomena such as violent
rainfalls and flows of melted snow which lead to considera-
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ble reshaping of the existing relief forms and the origin of
others (e.g, ravines). A single outflow can reach the level of
10-15 m 3/s;"km2 • On loess uplands such phenomena repeat
themselves every 30-50 years.
A characteristic feature of the Lublin Upland landscape is
the occurrence of wavy plateaus with relative heights reaching
20-40 m. Branching erosive-denudative dry valleys
are typical elements of relief in this area. Their bottom is
flat and accumulative, its width reaching 50 m, its slope 1 0 ,
and its length up to 2 km. The area of drainage basins in
dry erosive-denudative valleys reaches 2-3 km'.
Episodic channels belong to the most interesting structures
which form during violent rainfalls and thaws. The shape of
these forms resembles that of river-beds. They are formed
as a result of outflow concentration at the bottom of dry
erosive-denudative and basin-shaped valleys. Episodic
channels are therefore shaped by the same group of processes
as flat-bottomed temporary valleys (wadi) in the semiarid
zone. One can distinguish two basic types of episodic
channels: erosive and transportive-depositional. The character
of the channels depends of the degree to what the
terrain is covered with flora. In areas which are ploughed or
are used for growing root crops erosive channels develop.
These are shallow (0.1-0.15 m) and broad (2 m on average)
forms, the indicator of channel shape wid = 20. Erosive
channels develop in the ploughing layer (about 0.2 m).
Evorsion forms, which are 0.2-0.9 m deep, occur in their
bottoms only sporadically. Where the flora is relative rich
(crops, grass) material is deposited at first (considerable
roughness of subsoil) [depositational channels]. Subsequently,
when the speed of flows increases, the flora is laid,
which causes' a step decrease in roughness of subsoil (transportational
channels). Where the inclination is diminished
(local erosive bases, valley mouths), material is deposited
among blades and stalks of plants (depositational channels).
Flows in episodic channels which develop on loess uplands
of south-eastern Poland reach the average level of 1 rn'I s
(maximum 2-3 m' Is), the average speed of flows being 1.5­
1.8 m/s, The above-mentioned flows in episodic channels
whose drainage basins have the area of the few hectares are
comparable with flows of rivers whose drainage basins area
is 300 km'. Such high flows which are created during episodic
phenomena last only for 2-3 hours.
Seasonal changeability of conditions of development of the
forms under discussion is connected with human activity
(anthropogenical factor). It manifests itself in a temporal
lack of flora on plough-land. Therefore, episodic channels
are usually formed in autumn or spring. Despite the fact
that episodic channels develop in the same places every
few years, they are not long-lasting forms. They are destroyed
rather quickly as a result of ploughing.
Episodic channels are in a strict connection with episodic
phenomena which, as the research shows, belong to factors
that decide on the morphology of loess uplands of the temperate
zone. Above all, they initiate the creation of new
forms of configuration. The above facts confirm the opinion
that episodic phenomena play a leading role in the
contemporary development of relief in the areas under discussion.