  The Earth's surface is subdivided into eight large tectonic plates and many
smaller ones. We reconstruct the plate tessellation history and demonstrate
that both large and small plates display two distinct hierarchical patterns,
described by different power-law size-relationships. While small plates display
little organisational change through time, the structure of the large plates
oscillate between minimum and maximum hierarchical tessellations. The
organization of large plates rapidly changes from a weak hierarchy at 120-100
million years ago (Ma) towards a strong hierarchy, which peaked at 65-50, Ma
subsequently relaxing back towards a minimum hierarchical structure. We suggest
that this fluctuation reflects an alternation between top and bottom driven
plate tectonics, revealing a previously undiscovered tectonic cyclicity at a
timescale of 100 million years.
