كليدواژه :
كوه سيالان , البرز غربي , شواهد يخچالي , تغيير آب و هوا
چكيده لاتين :
Climate is the most important external factors in morphologic processes of the earth surface. Since the recent climatic conditions in the special geographical latitudes are not able to produce many of the existing phenomenon at the earth surface, such as glacial cirques, therefore it is possible to attribute such phenomenon to the climate changes of far past years (quaternary era) .The evidences due to glacial activities in Siyalan (west Alborz) are considered as the remaining phenomenon of the past climate conditions. So that, following the pervious researches, this study was performed by field and documentary observations and also by the instruments like topographic maps (1:50000, 1:25000), geographical maps (1:100000), aerial photos (1:40000) with the aim of recognizing the quaternary glacial phenomenon and their scope in the northern hill sides of Siyalan mountain located in west Alborz at the south part of Tonekabon town ship. The results obtained from the researches indicated that in the present climatic conditions of the area under study, the process of water erosion and destruction of rocks by freezing, ice melting and as a whole mechanical processes (from the height of 2000 up to 4100m) and at the places with heights of lower than 2000m, the destruction and cracking of rocks due to physical-chemical and bio-chemical processes are recognizable, Consequently ,the features and phenomenon related to these processes form the predominant landscape of mountainous areas, meanwhile at the height of 2500-4176 m, there exists some evidences including glacial cirques, moraines, glacial valleys,... based on glacial processes which indicates the climate conditions in quaternary era.
