Holocene slope dynamics in Sierra Nevada (south Spain). Sedimentological analysis of solifluction landforms and lake deposits
M. Oliva, A. Gómez Ortiz, 2011. "Holocene slope dynamics in Sierra Nevada (south Spain). Sedimentological analysis of solifluction landforms and lake deposits", Ice-Marginal and Periglacial Processes and Sediments, I. P. Martini, H. M. French, A. PéRez Alberti
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The activity of geomorphic processes in the current periglacial belt of Sierra Nevada during the Holocene has been strongly controlled by climate variability. We examined two sedimentary records showing several cycles with varying intensity of slope processes in the massif. Chronostratigraphic studies of solifluction landforms have revealed seven cycles of enhanced slope activity in Sierra Nevada during the last 7 ka. Lake sediments show eight periods with increased slope activity over the last 6 ka. Depending on temperature and moisture regime, erosion or conditions of slope stability prevailed. Cold and wet periods triggered slope processes and favoured deposition of coarse-grained sediments into the lakes, whereas warm phases were prone to soil development and fine-grained sedimentation in the lakes. The lake sediments also show evidence for an increasing aridity trend since the Holocene Optimum Warm Period in Sierra Nevada, which induced a shift of solifluction processes to higher elevations accompanying late-lying snow patches.
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Understanding the sediments deposited by glaciers or other cold-climate processes assumes enhanced significance in the context of current global warming and the predicted melt and retreat of glaciers and ice sheets.
This volume analyses glacial, proglacial and periglacial settings focusing, among others, on sedimentation at termini of tidewater glaciers, on hitherto not-well-understood high-mountain features, and on sediments such as slope and aeolian deposits whose clasts were sourced in glacial and periglacial regions, but have been transported and deposited by azonal processes. Difficulties are thus often encountered in inferring Pleistocene and pre-Pleistocene cold-climate conditions when the sedimentary record lacks many of the specific diagnostic indicators. The main objective of this volume is to establish the validity and limitations of the evidence that can be obtained from widely distributed clastic deposits, in order to achieve reliable palaeogeographic and palaeoclimatic reconstructions. At a more general level and on the much longer geological timescale, an understanding of ice-marginal and periglacial environments may better prepare us for the unavoidable reversal towards cooler and perhaps even glacial times in the future.