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
Venetia Diamond Mine Venetia Diamond Mine The Venetia Diamond Mine is South Africa's largest producer of diamonds. It is situated close to the South African town of Alldays in the Limpopo province and is located within the 360 km² Venetia Limpopo Nature Reserve. The open-pit mine is one of De Beers’ six remaining diamond mines in South Africa and the only major diamond mine to be developed in the country during the past 25 years. As such, the mine represents one of De Beers’ single biggest investments in South Africa. The mine was opened in 1992 by Harry Oppenheimer, a former De Beers