Regional specificities of the high-altitude periglacial in the Mediterranean domain

Abstract

Article in French.

ORIGINAL TITLE: Specificites regionales du periglaciaire d'altitude dans le domaine mediterraneen

Various sorts of periglacial phenomena can be observed in the mountains of different mediterranean regions. Permafrost cores exist in some narrow and pinpoint localized geomorphological units on the high massifs of the Southern Alps in the boundary zone between France and Italy, and also probably on the highest ranges in the Middle East; such sites admit active rock glaciers under the present climatic conditions, but the development of their feature and structure has requin;d a long time since the tardiglacial or the holocenic age. In reality the most widely distributed features of cold morphodynamic appear in a cryonival tier with some definite limits in altitude: superficial microforms as stone rings, stone stripes and terracettes are typically related with seasonal or pluriannual frost processes.

The inherited formations from the quaternary cold periods are present, also at moderate altitude, and their persistance is very important because they contribute to stabilize the environment. In the northern part of the mediterranean area the stratified slope deposits predominate, specially in the shape of "grezes litees" below inherited nival alcoves and at southerly or easterly exposure. In the mountains of Northern Africa quaternary cryonival slope deposits are also to be found, but the most frequent are less typical and their origin was related with multiple factors; however some real "grezes litees" exist also here in different sites.

In the high ranges of the Middle East a very original feature consists of long slopes on soft rock with a regular and linear profile, without detrital cover and without erosion gullies. The genesis of such forms, since the Quaternary up to now, is connected with different combined factors: arid tendance of the climate, hard and lasting seasonal frost in the soil, pellicular solifluction and superficial sheet running from melting snow or ice in spring.