Metastable domains, i.e. regions with perfect crystal patterns separat
ed by domain walls-chains of dislocations-are found to exist in parame
trically excited capillary ripples. Two typical mechanisms responsible
for the transition of ensembles of domains to perfect crystals are re
vealed: collapse of individual domains when the domain wall is a close
d contour of annihilating dislocations and merging of neighboring doma
ins due to the dislocation climb to the walls of a cell.