Glaciers in and / or on volcano craters; Network of glacier encompassing the summit at the outward flanks; Occurring in extinct or dormant volcanic craters which rise above the regional snow line (WGM
S 1970); Occurring in and /or on volcanic craters (WGMS 1977); Occurring in extinct or dormant volcanic craters (WGMS 1998)
A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. Some are over two billion year
s old. Cratons are generally found in the interiors of continents and are characteristically composed of ancient crystalline basement crust of lightweight felsic igneous rock such as granite. They have a thick crust and deep roots that extend into the mantle beneath to depths of 200 km. [Wikipedia]