  The spatiotemporal development of melting is studied experimentally in a 2D
dusty plasma suspension. Starting with an ordered lattice, and then suddenly
applying localized shear, a pair of counter-propagating flow regions develop. A
transition between two melting stages is observed before a steady state is
reached. Melting spreads with a front that propagates at the transverse sound
speed. Unexpectedly, coherent longitudinal waves are excited in the flow
region.
