  We report Monte Carlo studies of a two-dimensional soft colloidal crystal
confined in a strip geometry by parallel walls. The wall-particle interaction
has corrugations along the length of the strip. Compressing the crystal by
decreasing the distance between the walls induces a structural transition
characterized by the sudden appearance of a one-dimensional array of extended
defects each of which span several lattice parameters, a "soliton staircase".
We obtain the effective interaction between these defects. A Lindemann
criterion shows that the reduction of dimensionality causes a finite periodic
chain of these defects to readily melt as the temperature is raised. We discuss
possible experimental realizations and speculate on potential applications.
