Langlivann and Himtjern are two basins in a lake situated on rocks poor in lime and with coniferous forest and bogs in the surroundings. The lake is fundamentally oligotrophic. The influence of allochthonous organic matter is shown by lake colours which are different shades of brown, and by water colours which at the surface are from 15 to 25 on the mg Pt/1 scale.

Some differences in hydrology and morphology make the thermal and oxygen stratifications different in the two basins. At certain periods iron is accumulated in great quantities in the deep water. The differences, both in time and depth, in oxygen concentration make it possible to study the influence of this element on the reduction/oxidation of iron. An attempt has been made to find the critical concentration of oxygen. The value found by Einsele (1940) in eutrophic lake water seems also to be valid in this dystrophic lake.

The development of dichotomous pH stratifications is shown. They seem to confirm the above statement.