What is "aufeis"

n. naled (gloss: sheet-like layered mass of ice).

thumb|upright=1.15|A sheet of aufeis in a glacial valley in Mongolia Aufeis ( German for "ice on top") is a sheet-like mass of layered ice that forms from successive flows of ground water during freezing temperatures. This form of ice is also called overflow, icings, or the Russian term, naled. The term was first used in 1859 by A. T. von Middendorff following his observations of the phenomenon in northern Siberia.