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 on certain covenants of their investment agreement, but is working with Shear to find funding or a purchaser. The mine was developed, opened and operated by Tahera Diamond Corporation. The company was provided with CAN $35 million loan by Tiffany & Co. to assist in construction of the site, as part of a marketing alliance. The mine produced diamonds from 2006 to February 2008, and was Tahera's only mining operation. The company reported financial losses in 2007 due to operational difficulties, the high value of the Canadian dollar, high oil prices, and the short operating season of the Tibbitt to