pre-1840s I'm guessing there was at least one turn of the Wheel in the distant past, before the Black Rock's arrival. Somehow, Magnus Hanso knew roughly where and when the Island would reappear. He was exploring this region when the Island rematerialized under them, which is why the Black Rock is so far inland.
1840s-1970s Someone from the Black Rock (the first mate?) turned the Wheel, changing the Island's entrance to just outside Portland, which is how the Black Rock Ledger ended up in Madagascar. Richard may have begun using the Island during this period (circa 1950) as the location of his summer camp for special children.
1970s-2004 The Dharma polar bear turned the Wheel, changing the Island's entrance to the South Pacific and depositing the polar bear at its antipode in the Tunisian desert.
2004-? Ben turns the Donkey Wheel yet again, changing the Island's entrance to the antipode of wherever he landed in the desert. This is its current location.
