Climatic Geomorphology of Lebanese High Mountains

Abstract

Lebanese Mountains running along the eastern coast of Mediterranean Sea are about 3000 m high and consist of jurasic and cretaceous limestones. Several geomorphological phenomena derived from lithology and climatic conditions develop in these mountains.
Several undulated erosional surfaces which are strikingly contrast of deep valleys with high cliffs are well reserved. The limestone composing the Mountains is weak enough to be cut into deeply by water erosion but it resists to mechanical weathering, so the erosion is restricted only along the streams and the slopes and erosional surfaces are apt to be reserved.
At the head of the streams there are great cirque-like landforms, represented with “Cirque de Cedres” and have been regarded as glacial cirques by several authors. These landforms, however, are also ones derived from lithology and it is impossible to think them glacial cirques. These landforms seem to have been created by the landslides occured frequently under the different climatic conditions in the past.
Small hollows, distributing generally on the erosional surfaces above 2000 m high, have been often considered as nivation hollows. But these hollows seem to be karst landforms and their distribution is controlled with the underground water system. Therefore it is not correct to relate these hollows with firns.
Patterned grounds develop widely on the gentle slopes in the alpine zone of Lebanese Mts. For the formation of these landforms intensive destruction of bedrocks and productions of gravels and small particles are needed at first. The grain size composition under the present climate is favourable to the formation of patterned grounds.
In this Mountain tree limit altitude is estimated to about 2500 m high, though it is not clear at the present time. Astragalus and perrenial herbs (Vicia canescene) distribute instead of trees. Judging from this, the lower periglacial limit is estimated to have been at 2600-2700 m high. On the area above this lime debris production and movement were vivid, and the area below this line soil formation was predominant and patterned grounds occur only as extrazonal phenomena here.
Periglacial deposits belong Riss and Würm ice ages are observed around Qornet es Saouda and other places. These old deposits are consolidated. Riss deposits are coarser than Wurm deposits. And both deposits are coarser than the deposits on the present slopes.