finger-rafted ice

A floating piece of ice that meets and overrides another creates rafted ice—because one piece uses the other as a raft. When two pieces of rafting ice interlock with one another in narrow, alternating strips, like the fingers of folded hands, the ice is said to be finger-rafted. Rafting is the usual way fractured young or new ice, such as nilas, joins together to develop floes of larger size and greater thickness. As floes grow larger, instead of rafting when they collide, they fracture and buckle. The debris from these dramatic impacts creates the hummocks and pressure ridges that commonly distinguish the surface of pack ice.

Gretchen Legler