The Isua Greenstone Belt is an Archean greenstone belt in southwestern Greenland. The belt is aged between 3.7 and 3.8 Ga, making it the home of the oldest rock in the world. The belt contains variably metamorphosed mafic volcanic and sedimentary rocks. The occurrence of boninitic geochemical signatures offers evidence that plate tectonic processes may have been responsible for the creation of the belt. However, this has recently been disputed by earth scientists who offer up a new theory for the formation of the Isua Greenstone Belt.