The Volarnk Brook, a left tributary of the Soča River, springs below The Krn Mt. in gullies almost 2 000 m above sea level. The gullies are dry most of the year, they merge into three spring branches.
    Each of them is special in itself, but the common feature is a large number of waterfalls in brookbeds and korita with constant water. Its quantity increases by flow, as it is fed by many small springs in brookbeds and along them.
    Brook basin is built by various rocks. The oldest is the layered Dachstein limestone with layers and inlays of dolomite, about 210 million years old.
A small patch is formed by Jurassic or Liassic micrite and calcarenite limestone with chert poles and subordinate clayey marl, aged from 175 to 199 million years.
The bulk of the rocks are represented by various Cretaceous limestones. They are between 70 and 100 million years old.
The youngest ones are Ice Age moraine and screes, which are still forming.
    The surface is very uneven and steep, with intermediate small planes where the villages of Krn, Vrsno, Selce and Selišče were built, the last one a little above the outlet.
    The Volarnk flows into the Soča only 173 m above sea level.

Let's take a look at each of the spring branches:
    Mrzlca is the left one,
    Branch of the Simon Gregorčič waterfall is the middle one and
    Branch of the waterfall in Brinta is the right one.

Explanation of the names.