A thin elastic crust of ice, easily bending on waves and swell and under pressure growing in a pattern of interlocking "fingers" (finger rafting). Nilas has a matte surface and is up to 10 centimetres in thickness and may be subdivided into dark nilas and light nilas.
Environment and Climate Change - Canada https://www.ec.gc.ca/glaces-ice/default.asp?lang=En&n=2CE448E2%E2%80%931&offset=4&toc=hide