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Ahar river,the western tributary of Qara su drainage system is located on the north of eastern Azerbayjan.lts basil is the central part of a depression which sparates the salawat ¬
Qaradagh mountain ranges from the sabalan ¬Arasbaran ranges.
This river rises from kasaba mount (2960 m.)
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at the longitud of 46 20 E and running around
0 '
the latitude 38 30 N towards the east.The lengfu
of the basin is a little more than 100Km.andits
average width runs to 25 Km. The Qara dagh uplands on the north of the basin keeping W-E trend is
the continuation of Talesh mountain ranges. The southern uplands of the basin also is part of a long range which flanks from sabalan and trends
WNW into the jolfa region.Both ranges are of Alpine folded system.The immediately layout of
Pliocene deposit on the rocks of Eocene explains the formation of this basin during early pliocene MDrphologic evident connotes this depression as a rift valley which its bottom is tilted to the south. The asymmetry of the basin is because of this phenomenon.
The bottom of the basin resembels a kind of
plateau which is dissected by Ahar river and its Tributaries.At the margin of the basin several