Baydzharakh

Baydzharakh (Байджарах; Yakut: Бадьараах, Baçaraakh ) is a term based in the Yakut language, referring to a roughly cone-shaped natural rock formation. They are usually composed of siltstone, silty peat or loam.

Description
Baydzharakhs form owing to thermokarst activity in periglacial areas. They are the result of a cryolithological process by which polygonal ice-wedges thaw within the permafrost. These formations usually reach a height between 5 m and 10 m with an area at the base between 15 sqm to 20 sqm.

In the first phase of the ice melting process baydzharakhs have a pillar-like shape. When the ice mass in the surrounding rocks is high, they swell and form rounded depressions known as alas (Алаас) in Yakut. These depressions are usually between 8 m to 12 m in depth, but exceptionally may be 30 m deep. Baydzharakhs come often combined with alas depressions.

Baydzharakh formations are found in different places across the East Siberian Lowland, such as Muostakh Island, Stolbovoy Island, Kotelny Island and the Ulakhan-Sis Range, as well as in scattered places of the Yana-Indigirka Lowland. In 1950 a baydzharakh was the last vestige of now disappeared Semyonovsky Island in the Laptev Sea. They often occur together with Yedoma (Едома) complexes and in areas with ice-wedges of considerable thickness.