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
Catoca diamond mine Catoca diamond mine The Catoca diamond mine is the fourth largest diamond mine in the world, and is located in Angola. The mine is owned by a consortium of international mining interests, including Endiama (the state mining company of Angola) (32.8% ownership), Alrosa of Russia (32.8%), Odebrecht of Brazil (16.4%), and the Diamond Finance CY BV Group (16.8%). The mine is located on a kimberlite pipe. The mine had production of 1.8 million carats (360 kg) in 2000 and 2.6 million carats (520 kg) in 2001. Catoca management has been actively expanding capacity at the mine, such that the owners