Geology
Geologically the Siahan Range has never been fully studied but its general aspect is abrupt, rugged and broken. The Koh-e-sabz portion is composed of shale and volcanic rock, contorted in many places into fantastic shapes with synclinal and anticlinal curves. The shale which lies throughout in perpendicular parallel layers or at a slight angle to its base, gives the hill a very sharp and jagged appearance, but though difficult they are not unscalable, very steep and precipitous escarpments being rare and generally limited to the sides. The range being on consolidated upheaval, there are no valleys ascents and descents from one ridge to another being made by following the rivulets.
Read more about this topic: Siahan Range