“Flow-parallel structures” that “express the action of objects that either approach sufficiently close to or actually cut into a bed” (Allen 1982:510).
Marks of protracted contact (Allen 1982).
Drag marks, e.g., grooved shaped ice keel scour marks or iceberg drag marks (Allen 1982), which are the tracks made by bottom touching floating ice masses as their keels mechanically plough into soft sediments of lake, river, or ocean floors. Some grooves in Kasei Valles, Mars, are interpreted as ice keel scour marks. Ice keel scour marks may occur together with ice floe grounding pits (Woodworth-Lynas and Guigné 2003; Fig. 1).
Roll marks (Dżułyński and Walton 1965).
Marks of brief contact can be single or repeated and include prod marks, skim marks, etc. (Allen 1982).