Quaternary Glaciation in the Mediterranean Mountains: a New Synthesis

Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021 Quaternary glaciation in the Mediterranean mountains: a new synthesis P. D. HUGHES* & J. C. WOODWARD Geography, School of Environment, Education and Development, The University of Manchester, Manchester M13 9PL, UK *Correspondence: [email protected] Abstract: The Mediterranean mountains were repeatedly glaciated during the Pleistocene. Gla- ciers were present in most of the major mountains areas from Morocco in the west to the Black Sea coast of Turkey in the east. Some mountains supported extensive ice caps and ice fields with valley glaciers tens of kilometres long. Other massifs sustained only small-scale ice masses, although this was the exception rather than the norm. Glaciers still exist today and there is evidence that small glaciers were a common sight in many regions during the Little Ice Age. The Mediter- ranean mountains are important for palaeoclimate research because of their position in the mid- latitudes and sensitivity to changes in the climate regimes of adjacent areas including the North Atlantic. These mountains are also important areas of biodiversity and long-term biological change through the Quaternary ice age. All of this provided challenges and opportunities for Palaeolithic societies. This paper reviews the history of the study of glaciation in the Mediterranean mountains from pioneer nineteenth century observations through to the detailed geomorphological mapping and advanced geochronological datasets of recent times. We also review the current state of knowledge to frame the contributions presented in this volume. Lastly, this new synthesis then identifies outstanding research problems and assesses the prospects for new studies of glaciation in the Med- iterranean mountains. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license The mountains surrounding the Mediterranean Sea immediately to the east of the North Atlantic were repeatedly glaciated during the Quaternary. Ocean and aligned along the low mid-latitudes, Glacial processes have been important agents of the Mediterranean basin is an important corridor long-term landscape modification and classic gla- for westerly atmospheric circulation between the cial scenery has been documented across this region. Sahara Desert and the Alps. Today, moisture-bear- As in other parts of the world, the influence of these ing atmospheric depressions – generated both in glaciers was not confined to the uplands because the North Atlantic Ocean and in the Mediterranean meltwaters carried large volumes of outwash sedi- basin itself – are able to penetrate eastwards to cen- ment through the downstream reaches of river tral Asia. This situation may have been more mar- basins – this glacial signal can be traced to the Med- ked during Pleistocene cold stages at those times iterranean coast and offshore. The geomorphologi- when both the oceanic and atmospheric polar fronts cal and sedimentological record of glaciation in were much further south than today, with the for- these mountains is now providing valuable infor- mer positioned off Iberia in the North Atlantic mation on past climates because the viability of Ocean (Ruddiman & McIntyre 1981; Roucoux glaciers is closely related to atmospheric air temper- et al. 2005). atures and moisture supply. The glacial record can The mountains of the Mediterranean represent be compared with modern climate data to generate dynamic landscape systems that are highly respon- information on the nature of winter moisture sup- sive to climate change (Tzedakis et al. 2004; Regato ply (as snow) and summer temperatures during & Salman 2008; Woodward 2009; Vogiatzakis Pleistocene cold stages. These data usefully com- 2012). There is now a large body of evidence show- plement the rich body of proxy climate data that has ing that the mountainous peninsulas of southern been retrieved from other Mediterranean archives, Europe, as well as the mountains of North Africa, including lake basins, speleothems and the marine hosted biotic refugia during Pleistocene cold stages sedimentary record (Woodward 2009). (Tzedakis 1993; Hewitt 2000). It is mainly from The Mediterranean region is situated in an these refugia in southern Europe that plants and important position for understanding Quaternary animals colonized central and northern Europe dur- climate change in the northern hemisphere. Lying ing interglacials. The presence of glaciers in these From:Hughes,P.D.&Woodward, J. C. (eds) 2017. Quaternary Glaciation in the Mediterranean Mountains. Geological Society, London, Special Publications, 433, 1–23. First published online November 4, 2016, https://doi.org/10.1144/SP433.14 # 2017 The Author(s). Published by The Geological Society of London. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021 2 P. D. HUGHES & J. C. WOODWARD refugial centres during Pleistocene cold stages has (Almagia` 1918; Sestini 1933). The French scholar important implications for moisture supply as well Emmanuel de Martonne was a widely travelled as temperature; large glaciers in the uplands would geographer who undertook glacial research across have limited the availability of ‘temperate’ refugial the Mediterranean and beyond, from Morocco sites in topographically sheltered sites such as valley (Martonne 1924) to Romania (Martonne 1907, floors. Moreover, the association of glaciated 1922). Other key figures who worked across the Mediterranean uplands and their meltwater rivers Mediterranean were: Klebelsberg, who worked in with zones of Palaeolithic human activity and Spain, Italy and Greece (e.g. Klebelsberg 1928, migration routes (Woodward et al. 1995; Gamble 1930, 1931, 1932a, 1932b, 1933–1934); Suter, 1999; Gibert et al. 2003) highlights the importance who worked in Italy (e.g. Suter 1932, 1934); and of understanding environmental conditions in Med- Louis, who worked extensively in the Balkans and iterranean mountain catchments during Pleistocene Turkey (e.g. Louis 1926, 1944). Glacial research cold stages. in the Mediterranean was particularly active in the This introduction provides a critical review of inter-war period between 1920 and 1940 (see current knowledge of glaciation in the Mediterra- reviews in Messerli 1967; Hughes 2012; Ehlers nean mountains from Morocco to Turkey. The et al. 2016). Glacial geomorphological research in aims of this introduction are to: (1) provide the the region once again flourished after the Second background to the history of glacial research in the World War, especially in the 1950s, 1960s and Mediterranean mountains; (2) introduce the papers early 1970s, with notable research in Morocco in this volume; (3) examine the current state of (e.g. Mensching 1953, 1960; Wiche 1953), Monte- knowledge regarding Pleistocene glaciation in the negro (Liedtke 1962) and Greece (e.g. Hagedorn Mediterranean mountains; (4) review the recent 1969), all published in German. and current extent of glaciers in the Mediterranean As is clear from the Foreword to this volume, mountains; and (5) set out a new agenda by discuss- the most intrepid and geographically wide-ranging ing progress, problems and prospects for the study researcher in the two decades after the Second of glaciations in the Mediterranean mountains. World War was the remarkable Swiss scholar Bruno Messerli, who produced important papers on the The glacial pioneers glacial geomorphology of the Sierra Nevada in Spain (Messerli 1965a), Mount Erciyes in Turkey There is a long history of glacial research in the (Messerli 1964, 1965b), the mountains of the Leba- Mediterranean mountains. Some of the earliest non (Messerli 1966) and even the Tibesti Mountains papers on this topic are listed by country and region in Chad (Messerli 1972). Bruno Messerli’s classic in Table 1. By the end of the nineteenth century review of glaciation (Messerli 1967), based on 364 nearly all the Mediterranean mountain ranges were cited publications, was the first to illustrate the full known to have been glaciated in the Pleistocene scope of Pleistocene glacial activity across the entire (Table 1). These early glacial studies involved Mediterranean region. Messerli’s research, how- some of the key figures in geographical research in ever, was followed by a period of relative stagnation the early twentieth century, including Jovan Cvijic´ in the development of ideas and fresh approaches and Albrecht Penck in the lead up to the First that lasted for almost three decades. One reason World War and Emmanuel de Martonne in the for this very limited progress was the difficulty 1920s (Ehlers et al. 2016). Jovan Cvijic´ was one involved in dating glacial deposits and landforms of the first geographers to appreciate the extent of – a problem not restricted to the Mediterranean glaciation in southeast Europe and worked exten- mountains in this period. Mediterranean glacial sively in the Balkans in the late nineteenth and research lost momentum because most of the glaci- early twentieth centuries (Cvijic´ 1899, 1900, 1917 ated areas had been identified and the extent – if not and references cited therein). Albrecht Penck – bet- the age – of glaciation was relatively well known. In ter known for his classic glacial work in the Alps – addition, international research in key parts of the was another of the Mediterranean glacial pioneers; Mediterranean was hampered by political tensions, he worked in the Pyrenees and the Dinaric Alps such as

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