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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

2009

Vol. 57, nr 7

614-618

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.

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

Zasadni J.

Przegląd Geologiczny

2009

Vol. 57, nr 7

607-613

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.