In 1892–1894, and again in 1900–1902, Baron Eduard von Toll explored the Laptev Sea in the course of two separate expeditions. On the ship "Zarya", Toll carried out geological and geographical surveys in the area on behalf of the Russian Imperial Academy of Sciences. In his last expedition Toll disappeared off the New Siberian Islands under mysterious circumstances. Toll noted sizable and economically significant accumulations of perfectly preserved fossil ivory in recent beaches, drainage areas, river terraces and river beds within the New Siberian Islands. The later scientific studies demonstrated that the ivory accumulated over a period of some 200,000 years.