جغرافیا و توسعه (May 2015)
Reconstruction of the Last Glacial Snow Lines by the Evidences of Glacial Periods in North West Zagros (Case study: Anticline Qalajeh)
Abstract
Existence of glacier and sub glacier landforms on Qalajeh mountains indicates the climate changes and changes in morphogenic boundaries. The main problem of the research is identifying cold glacier and sub glacier territories and estimating snow line height in folded Zagros due to lack of any study in this area. Therefore, the purpose is to identify evidences and prove the dominancy of existence of glacial morphogenesis territory and determine snowline of the last glacial period on Qalajeh heights. Topographic and geology maps, IRS satellite images, and monthly temperature and precipitation climate data are the main tools and data for research. Using satellite images and several field visits, the position of the area's cirques were identified and the past snow and ice equilibrium line (ELA)were reconstructed. Porter and Wright's method were used to estimate snow line for the last glacier and the current one. Ki squared test (Pearson) used to calculate the relationship between the spread and distribution of cirques with roughness aspects. Using Porter and Wright methods, Worm’s Snow-line obtained at height 2019 and 2015 meters respectively. Also water and ice equilibrium line at the north and south slopes obtained 2033 and 2075 meters respectively and ELA of area is equal to 42 meters. Results of Ki squared test showed that there is a significant relationship between cirques formation with geographic and roughness sides. Circus of the study area has more spread on the north sides. So 66.7 percent of the region’s circus have formed at the northern slopes and 33.3 percent of them are in the south ranges. Comparison of the results of the climate models and geo-morphological evidences of the last glacial period, proved the existence of glacier territory on above 2000 meters in Qalajeh mountain.
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