Late Pleistocene glacial evolutionary stages in the Gredos Mountains (Iberian Central System)

摘要

During the Last Glacial Period (Late Pleistocene) the summits of the Gredos Mountains (Iberian Central System) were covered by plateau glaciers and later evolved into valley and slope glaciers. The evolutionary sequence of these paleoglaciers has been obtained using geomorphologica! indicators and taking the "principal moraine" as reference. These moraines show the limit between the glaciation and deglaciation periods. In the glaciation period (G), four chronologically sequenced stages have been identified: the local glacial maximum or maximum ice extent (GM); limited retreat (LR); re-advance (RA); and finally major stabilization, the steady-state stage of greatest glacial stability (MS). In the deglaciation period (D), six chronologically sequenced stages have been identified: an absolute retreat which involved regression and stabilization (D1), two major retreat periods (D2 and D4) and two stabilization periods (D3 and D5). Finally, the last stage represents the complete disappearance of the glaciers (D6). This evolutionary sequence allows more precise studies of the ages assigned through numerical dating procedures and of the correlation of the paleoglaciers in the Gredos Mountains with those of other regions.