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
Ekati Diamond Mine company. The next kimberlites to be developed at Ekati will be mined using open pit methods and are named Jay and Sable, discovered in 1993 and 1995, respectively. Underground mining of the Misery kimberlite will commence in 2020, after open pit operations have been completed. Ekati Diamond mine, which is currently operated by Dominion Diamond is scheduled to remain operational until 2033. On November 13, 2012, CBC reported that the Harry Winston Diamond Corporation (now: Dominion Diamond Mines), 40% owners of Diavik Diamond Mine, would buy Ekati for US$500 million. Diamonds at the Ekati site are found in 45- to