Environmental Engineering Reference
In-Depth Information
In many areas, glacial deposits record glaciations during multiple Pleistocene
cold stages. The oldest and most extensive glaciations occurred during the Middle
Pleistocene, before the last interglacial (c. 125-110 ka) and the last cold stage
of the Late Pleistocene (c. 110-11.7 ka) - see van Kolfschoten et al. (2003) and
Walker et al. (2009) for chronostratigraphical definitions of the Late Pleistocene. In
northwest Spain Middle Pleistocene glaciations have been shown using cosmogenic
nuclide analyses (Vidal-Romanı et al. , 1999; Fernandez Mosquera et al. , 2000;
Vidal-Romanı and Fernandez-Mosquera, 2006), whilst in Greece Middle Pleis-
tocene glacial deposits have been recognized using uranium-series dating (Hughes
et al. , 2006b). Elsewhere, in places such as Corsica, the central Balkans and parts
of Turkey, cosmogenic nuclide analyses suggest that the most extensive recorded
glaciation occurred during the last cold stage of the Pleistocene and no evidence of
earlier glaciations has been reported (Kuhlemann et al. , 2008, 2009; Ak¸ar et al. ,
2007; 2008). The timing of glacier advances may have been asynchronous across
the Mediterranean, and the extent of glaciations also appears to have varied between
regions during different Pleistocene cold stages (Hughes and Woodward, 2008). A
detailed review of the current state of knowledge of Pleistocene glaciations in the
Mediterranean is provided below, region by region.
3.2.1 Atlas Mountains, North Africa
The Atlas Mountains contain the highest mountains of North Africa and some of the
highest mountains surrounding the Mediterranean Basin, several of which exceed
4000 m asl. As a consequence of the high elevation of the High Atlas, large glaciers
formed during the Pleistocene especially in the High Atlas. However, no glaciers
survive today (Hughes et al. , 2011b).
The largest glaciers formed in the Toubkal massif (4167 m asl), where valley
glaciers emanated from a central ice field that formed between the two high-
est summits, Toubkal (4167 m asl) and Ouanoukrim (4067 m asl). The northern
outlet glacier draining this ice field extended nearly 10 km to an altitude of just
2000 m, about 1 km down-valley of the shrine of Sidi Chamarouch. Valley glaciers
also formed on the northern slopes of Aksoual and Bou Iguenouane. Well-defined
cirques are present in the upper catchments around Toubkal and on the northern
slopes of Aksoual and Bou Iguenouane, and these cirques contain moraines (Fig-
ures 3.2 and 3.3). In some glacial valleys, large landslides are closely associated
with moraine complexes (Figure 3.4). Beryllium-10 exposure ages suggest that
glaciers formed in the High Atlas during the Younger Dryas - a well-known cold
reversal in the North Atlantic region. A lower set of moraines have yielded 10 Be
exposure ages close to the global Last Glacial Maximum (LGM) whilst the lowest
Note: ages are abbreviated in thousands of years (e.g. 40 500 years
40.5 ka). Radiocarbon ages are pre-
sented as 40 ka 14 C BP, with BP standing for 'before present' (AD 1950). Calibrated radiocarbon ages are
denoted as 40 cal. ka.
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