Petru Urdea

The aim of this paper is to present some new data from Pleistocene glacial deposits of some key areas in the Southern Carpathians, Romania. The results from detailed geomorphological mapping and surface exposure dating (10Be) in the Retezat, Făgăraş and Parâng Mountains give insight into their Pleistocene glacial history. The Southern Carpathians are the highest mountain chain of the Romanian Carpathians, with 11 peaks higher than 2500 m a. s. l. Although evidence for Pleistocene glaciation in the Romanian Carpathians was pointed out over 125 years ago, the timing and extent of the glaciation is still controversially discussed. In the Retezat Mountains we focused our field work and boulder sampling on the north-facing Pietrele Valley, in the Parâng Mountains we worked in the northfacing Jieţ valley. We present new results from geomorphological mapping from the eastern and central part of the Făgăraş Mountains, where landsliding and steep valley walls impede exposure dating. Two major glacial advances, M1, and M2 (in local terminology Lolaia and, respectively, Judele-Jieţ) have been previously described. The most extensive M1-advance reached an elevation of 1,035 m a.s.l. in the Retezat Mts., some 250 m below the terminal moraines of the M2- advance. The timing of the M1 advance is uncertain but it occurred either during the Early Würm (MIS4) or during the Riss (MIS6) glaciation, based on the relative chronology of pedological investigations. The exposure ages show that the younger M2 glacial advance (Judele-Jieţ) was deposited during the late glacial at 16.8±1.8 kyr in the Retezat Mountains and 17.9±1.6 kyr in the Parâng Mountains. There is no evidence in the field for a glacial advance during the global Last Glacial Maximum (LGM); we therefore conclude that the glacial advance during the LGM was moisture-starved and therefore less extensive than the late glacial advance, which overran the LGM deposits. This is in good agreement with the sealevel data from the Mediterranean Sea, the moisture source for the region. The new investigations and geomorphological mapping in the eastern part of Făgăraş Mts. (Luţele-Berevoiescu area) allow establishing a stepwise evolution of glaciers in the last stages of the Pleistocene and allow differentiating between two ways of evolution of glaciers in their extinction stage, one in a normal ablation way, and the other one from glaciers to rock glaciers. .

The article describes the glacial relief and the development of Pleistocene glaciation for one of the most representative mountain units of Romania, the Retezat Mountains, with special attention to the glacial cirques and valleys. Some morphometric elements have been used to analyze the specific way in which the glaciers have modeled the relief of Retezat Mountains - the surface area, the perimeter and circularity index for glacial cirques and depth, valley top width and form ratio for glacial valleys, as well as the relations between them expressed by regression equations. Assimilating the longitudinal profile of the cirques of a logarithmic curve y = k(1-x)e-x that describes the concavity of the longitudinal profile, we found together with the known values 0.5, 1 and 2 of the constant k, that describes the concavity of the longitudinal profile, there are cirques that need the new value 1.5. The geomorphological mapping has allowed a reconstruction of the development of the Pleistocene glaciation in this mountain area. In the Lolaia phase, (Riss II), the maximum phase, the glaciers occupied 25 % of the surface of these mountains, reach down to 1035-1100 m.a.s.l., and the altitude of the perennial snow limit is placed at 1646 m, the longest glacier, Lăpuşnicu Mare having 18.1 km. The last glaciers existed in the Younger Dryas (Beagu phase) in which there were only very small lens shaped glaciers, only in the cirques situated at an altitude of over 2150 m.