The Bering Strait, the Chukchi Sea to the north and the Bering Sea to the south, are all shallow seas ("maps, right"). During cycles of global cooling, such as the most recent ice age, much water became concentrated in the ice caps of the Arctic and Antarctica. The drop in sea levels exposed shallow sea floors that have subsequently re-flooded. Other land bridges around the world have been created and re-flooded in the same way: about 14,000 years ago, mainland Australia was linked to both New Guinea and Tasmania. The British Isles were an extension of continental Europe via the dry bed of the English Channel; and the dry basin of the South China Sea linked Sumatra, Java and Borneo to the Asian mainland.