Continental rifting and collisional events in the last 1000 My indicate two types of supercontinent cycles: one in which breakup of one ? supercontinent is followed by formation of another supercontinent, and one in which a new supercontinent forms ? long-lived, small supercontinents, which never fragment or incompletely fragment due to insufficient mantle shielding. The small supercontinents may form over linear, ? nnected subduction arrays rather than over a region with a high density of closely connected subduction arrays.