What continent does a city reside in? Here's one simple solution to the
dilemma: Each land spark (or clump) is given an ID. As the world is
generated, this ID is propagated to each offspring land cell.
It consumes memory - 1 byte/cell worst case; 1 bit/cell best case.
This doesn't address the problem of naming oceans.
Two or more sparks may generate a single continent ("Eurasia"). How
confusing will this be?