Østmarka is marked by its location on top of basement rock (more than 1 billion years old) containing easy-to-see folds that make up valleys and hills in the north-south direction.
The purpose of the protection is the conservation of a substantial, relatively untouched coniferous forest along with plant and animal life typical for this part of Oslomarka, and which has particular scientific and educational significance.
During the period when small sawmills were being increasingly used throughout the forests of Oslomarka and the timber export became a substantial industry - from ca 1750 and well into the 19th century - this engendered a big need for transportation.
In Østmarka alone there were over 2,000 drivers and 4-5000 horses occupied with moving planks between Øyeren and Kristiania (today Oslo).
The Plank Road starts at Eikeberg and Børter in Enebakk - it crosses the ice on Børtervann and moves up to Rausjø and turns up towards Vangen and Skjelbreia, further over Eriksvann, Søndre Skytten, Elvåga, across to Nøklevann, Rustadsaga, Østensjøvannet and down to the city.