100 Years of Solitude 16-20

Considering that Macondo was founded on incest and murder, and has continued spawning those things ever since, of course it has to be destroyed. The biblical version of the flood story says the flood was caused because God needed to rid the world of evil, which at the time, was most of the population. Macondo has lived through every tragedy and evil possible, and since that is what it fed on, it is now time to be destroyed. Ursula becoming doll like is a signal that there is no more spiritual glue to hold the place together, its moral conscience. She is too old to fulfill that role, and no one who might be a decent successor to the position. There really isn't anything more for the town to go through except death.