Location of Lahijan

Except at their northern end, where the Heyran pass at the top of the Āstārāčāy valley does not exceed 1600 m, they are over 2,000 metres (6,600 ft) high, with three spots over 3,000 metres (9,800 ft) including the BaqrowDaḡ, the AjamDaḡ, and the Shah Moʿallem or Masouleh Daḡ. Their eastern and northeastern side is deeply carved by parallel streams flowing down towards the Caspian, resulting in a comb-shaped pattern. The western Alborz itself, to the east of the Safid-rud valley, is wider and more intricate, with three parallel (WNW-ESE) ranges; the southernmost and lowest one is represented in Gilan by the Asman-saraKuh in the Ammarlu district; the medium one is the most continuous, from the Kuh-e-Dalfak to the KeramKuh, whereas the transversal valley of Polrud clearly divides the northern range into Kuh-e-Natesh and Kuh-e-Somam or Somamus, the highest spot of Gilan. All these mountains have a very complicated geological structure and tectonic history which connects them to the structural complex of central Persia.

Though all those mountains cover a greater area than the plains, these are the most specific feature of the province, and locally, the word Gilan often refers to the plain areas or particularly to the central plain.

This large parallelogram of lowlands is heterogeneous and can be divided into two main parts: the delta of the Safid-rud in the east and the Fumanat plain in the west. The former has been entirely built by the Safid-rud, a river with a high discharge and a high alluvial content. The higher part is made out of coarse ancient alluvial material, whereas in the lower part, north of Astaneh-e Ashrafiyyeh, the river often changed its course