Bundahishn 8

As the evil spirit rushed in, the earth shook, and the substance of mountains was created in the earth.

First, Mount Albûrz arose; afterwards, the other ranges of mountains (kôfânthâ) of the middle of the earth; for as Alburz grew forth all the mountains remained in motion, for they have all grown forth from the root of Albûrz.

At that time they came up from the earth, like a tree which has grown up to the clouds and its root to the bottom; and their root passed on that way from one to the other, and they are arranged in mutual connection.

Afterwards, about that wonderful shaking out from the earth, they say that a great mountain is the knot of lands; and the passage for the waters within the mountains is the root which is below the mountains; they forsake the upper parts so that they may flow into it, just as the roots of trees pass into the earth; a counterpart (ângunfaitak) of the blood in the arteries of men, which gives strength to the whole body.

In numbers, apart from Albûrz, all the mountains grew up out of the earth in eighteen years, from which arises the perfection of men's advantage.