Permafrost by permafrost. Of this area slightly more than half is underlain by continuous permafrost, around 20 percent by discontinuous permafrost, and a little less than 30 percent by sporadic permafrost. Most of this area is found in Siberia, northern Canada, Alaska and Greenland. Beneath the active layer annual temperature swings of permafrost become smaller with depth. The deepest depth of permafrost occurs where geothermal heat maintains a temperature above freezing. Above that bottom limit there may be permafrost, whose temperature doesn't change annually—"isothermal permafrost". Permafrost typically forms in any climate where the mean annual air temperature is less than the
Jericho Diamond Mine Contwoyto ice road in 2006. Tahera filed for protection from creditors in January 2008, and the mine stopped recovering diamonds once existing ore stockpiles ran out, one month later. There is no registered airport at the site so all heavy equipment had to be brought in by the Tibbitt to Contwoyto winter road. Due to the remoteness of the site the mine was part of the impetus for a proposal to build a port near the community of Bathurst Inlet with a road to both Diavik Diamond Mine and Ekati Diamond Mine. The mine was estimated to be able to