Extent, timing and palaeoclimatic significance of Late Pleistocene glaciation in the High Atlas, Morocco

• Main Authors: Hughes, C., Fink, D., Fenton, C.R.
• Format: Conference Object
• Language: English
• Published: 2012
• Subjects: North Atlantic
• Online Access: https://research.manchester.ac.uk/en/publications/f4f57637-b392-4d31-ab80-0d51a3b26660; https://pure.manchester.ac.uk/ws/files/33527476/FULL_TEXT.PDF

Glacial geomorphological mapping, 10Be cosmogenic exposure ages of 30 erratics from 3 valley systems and palaeoglacier-climate modelling in the highest peaks of the Atlas Mountains, Morocco (31.1°N, 7.9°W), provides new and novel insights as to the history and evolution of the largest desert region on Earth. The Atlas Mountains display evidence of extensive and multiple late Pleistocene glaciations whose extent is significantly larger than that recognised by previous workers. The largest ice field and valley glaciers formed in the Toubkal massif and here we find 3 distinct phases of glacial advances within the Last glacial cycle. The oldest moraines occurring at the lowest elevations have yielded 10Be ages from 30.5 to 87.3 ka. Five of seven samples from moraines at intermediate elevations gave ages of 13.8 to 24.2 ka (2 outliers) which correlates well with the global Last Glacial Maximum (ca. 22-19 ka) and the last termination. Five erratics from the youngest and most elevated moraines yielded a suite of well peaked exposure ages from 11.1 to 12.9 ka which unequivocally falls within the northern hemisphere Younger Dryas (12.9-11.7 ka) chronosequence. The glacial record of the High Atlas effectively reflects moisture supply to the north-western Sahara Desert and can provide an indication of shifts between arid and pluvial conditions. The low altitude range from 2000-2500 m of the glaciations in all three glacial episodes recorded in the High Atlas indicate that climate was not only significantly cooler than today, but also very much wetter. The new evidence on the extent, timing and palaeoclimatic significance of glaciations in this region has major implications for understanding moisture transfer between the North Atlantic Ocean and the Sahara Desert during Pleistocene cold stages. Glacier advance in the High Atlas during this interval provides insight into the seasonal distribution of precipitation and provides valuable insight into the respective roles of moisture supply from the North Atlantic depressions ...