The "lower Ölgraben" is a tributary of the Isar and comes from the Karwendel and Karwendel foothills. A bit upstream there is also the Oberen Ölgraben. The streams are called oil ditch because in their area there was oil shale mining. Oil shale mining in the upper Isar valley and in the neighboring Tyrolean communities of Scharnitz, Seefeld and Reith can look back on a long shared tradition. Stone oil was extracted from local farmers as early as the 14th century. Itinerant traders, so-called Dirscheler or Öltrager, peddled their goods in order to barter with the remedy. Dirschenöl, shale oil or mountain oil - the vernacular knows various names for the oil, which has a strong smack of asphalt - was an indispensable miracle cure for people and animals in everyday use. Due to the high content of organically bound sulfur, it has an anti-inflammatory effect and promotes the healing process in the joint and wound area. The strong-smelling folk medicine, a black, strong-smelling oil, was obtained by heating rock mixed with so-called bitumen. The mining areas on the Bavarian side were in the upper Isar valley between Wallgau and Vorderriss. Oil shale was mined there in the Ölgraben mine until 1960. The owner was the Ichtyol company Cordes, Hermanni & Co from Hamburg, which operated another mine extremely successfully in the Seefeld and Reith area. Here, too, oil shale was mined until 1964 and processed in the Maximilianshütte in Reith near Seefeld. Nowadays the oil is imported from France from a plant belonging to the group of companies. However, further processing still takes place in Tyrol, where the company Ichthyol Gesellschaft in Reith manufactures the basic substance for numerous medicines.