In Castle Roogna, Dor accidentally put a forget spell on the Gap Chasm (the huge rift that splits Xanth in two), while trying to escape a horde of harpies and goblins, with the result being that everyone forgot the Gap Chasm existed, with the exception of the people who live near it. In this book, the forget spell is beginning to disintegrate into "forget whorls" spinning off into the nearby forest (due to the Time Of No Magic caused when Bink released the Demon X(A/N)th), causing confusion and memory loss. Ivy ends up walking through a forget whirl and it causes her to forget how to get home.
