Happens on lakes in Wisconsin. See [0] for a very interesting example of what happens when one gets real big and floats away.
Brigadoon is a musical with book and lyrics by Alan Jay Lerner and score by Frederick Loewe.[1] The plot features two American men who stumble upon Brigadoon, a mysterious Scottish village that appears for only one day every 100 years; one man soon falls in love with a young woman from Brigadoon.