A two-dimensional outcrop pattern resulting from the superimposition of two or more sets of folds of different generations. The form of the patterns seen depends on the relative attitudes of the superimposed folds; J. G. Ramsay (1967) recognized four basic types: redundant superposition (in which later folding has not altered the original pattern); dome and basin (egg box); dome–crescent–mushroom (see crescent-and-mushroom); and convergent–divergent (double zig-zag).