part of partially_surrounded_by adjacent to composed primarily of mountain glacier plateau ice field structural basin snow glacier ice field 2019-01-17T17:14:54Z The definition in the GCW assessment notes that the depth of snow or ice must be of "a substantial depth". This is in need of specification. When the thickness become great enough, tongues of ice overflow the basins or plateaus as Valley Glaciers. An ice field which is constituted by a continuous accumulation of snow and glacier ice that completely fills a mountain basin or covers a low-relief mountain plateau. glacial ice