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Glacial geomorphology and Pleistocene glacier reconstruction in the Demänovská Valley, Low Tatra Mountains, Slovakia

Pyrda Agata

Geology, Geophysics and Environment

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2023

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Vol. 49, no. 1

19--36

EN

In the Western Carpathians, clear evidence of the Pleistocene glaciations only occurs in two mountain massifs – the Tatra and Low Tatra Mountains. The Low Tatra Mountains (2043 m a.s.l.), contrary to the higher and more strongly glaciated Tatra Mountains (2654 m a.s.l.), have previously been much less attractive for scientific research. Hence, in these mountains both glacial landforms and chronology, together with a detailed reconstruction of glacier geometry and resulted equilibrium line altitude (ELA), are poorly documented. The aim of this paper is to characterize the glacial relief and reconstruction of geometry and ELA of the Zadná voda glacier in the Demänovská Valley system which belongs to the category of the largest Pleistocene glaciers on the northern slope of the Low Tatra Mountains. The mapping results show that a freshly shaped, massive terminal moraine of maximal ice extent (MIE, likely formed during the global Last Glacial Maximum – LGM) occurs 4.3 km distance down-valley from the glacial cirque backwalls. There is no evidence of deposits from older glaciations beyond the terminal moraine down the valley. The terminal zone of the MIE features a fresh morainic landscape with hummocky topography with kettle hollows and the only known morainic lake in the Low Tatra Mountains – Vrbické pleso. During the MIE, the Zadná voda glacier covered 7 km2 of the area and featured a mean thickness of 48 m. The ELA of this glacier was 1433 m, determined by the area-altitude balance ratio (AABR) 1.6 method, which is a similar value to the LGM ELA calculated in the Western Tatra Mountains. The recessional stages were only recognized in the cirques area, where one or two generations of debris-covered glaciers and rock glaciers mark the final deglaciation of the study area.

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Zasięg i geometria powierzchni lodowca Białej Wody podczas maksimum ostatniego zlodowacenia w Tatrach Wysokich-odpowiedź na krytyczne uwagi

Makos M., Nowacki Ł.

Przegląd Geologiczny

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2009

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Vol. 57, nr 7

614-618

EN

This paper is an answer to the polemical article Critical remarks on reconstruction of surface geometry of glaciers in the Polish High Tatra Mts. by Jerzy Zasadni in current issue of Przegląd Geologiczny. The criticism concerns our paper on reconstruction of surface geometry of the last glacial maximum (LGM) glaciers in the Polish High Tatra Mts. (drainage basins of Roztoka and Rybi Potok), published in Przegląd Geologiczny vol. 57, no 1, 2009. The main objections of our opponent concern on our reconstruction of equilibrium line altitude (ELA), ice surface geometry and paleoclimatic interpretations.We present a new reconstruction of ice surface geometry within the drainage basin of BiałaWoda during the last glacial maximum (LGM), including the part of a glacier previously omitted. The model of the glacier was made on the basis of detailed field mapping of glacial trimlines and analysis of digital elevation model (DEM) of the BiałaWoda Valley. The glacier surface area was found to be 37,61 km2. We found ELA value for AAR = 0,67 to be consistent with previously calculated average ELA value of 1430 m a.s.l. for AAR = 0.4, 0.45 and 0.5. In turn, some uncertainties concerning ice surface geometry in ablation area may be best explained as due to inaccuracy of geomorphological data, whereas the well-established ice surface elevation within accumulation area does not show any theoretical errors.We also show that glaciological parameters (t values along the glacier profile), questioned by our opponent, are consistent with glaciological conformities.We want to admit that paleoclimatic interpretations of paleocirculation presented in the ,previous paper was rather untimely.

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Krytyczne uwagi na temat rekonstrukcji geometrii powierzchni lodowców w polskich Tatrach Wysokich

Zasadni J.

Przegląd Geologiczny

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2009

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Vol. 57, nr 7

607-613

EN

The paper presents critical remarks on reconstruction by Makos and Nowacki (2009). The authors worked out a model of ice-surface geometry and equilibrium line altitude (ELA) of glacier which existed in the Białka Valley system (High Tatra Mts.) during the Last Glacial Maximum (LGM), utilizing mapped trimlines in accumulation areas and literature data about glacier extent in ablation areas. Some palaeoclimate implications from this study indicate LGM-modern temperature amplitude ca 5.5grade C from ELA depression and prevailing southern atmospheric circulation pattern during the LGM in the Tatra Mts. The reconstruction does not comprise the whole former glacier system of the valley and therefore the use of arbitrary assumed accumulation area ratio (AAR) resulted in considerable error in determinations of ELA. It is concluded that ELA calculated for 1400 m a.s.l. was obtained with AAR 0.77 value instead of intended 0.65–0.67. Critical remarks also concern ice-surface geometry which is in some places inconsistent with glaciological conformities. The LGM modern temperature amplitude was calculated without considering precipitation changes between LGM and modern time and on the basis of questionable position of modern ELA position, therefore it can not be treated as a valuable one. Similarly, the thesis about southern atmospheric circulation is here discussed in detail. It is concluded that the evidences presented by Makos and Nowacki (2009) can not support nor contradict this thesis. It should be treaded as a speculation made under the influence of Alpine results.