Map of the Celebes Sea region where biogeographic patterns observed on land led to lines drawn to explain breaks in species distribution. INDEX exploration of the deep sea will occur across Wallace's line – an imaginary line postulated by A. R. Wallace as the dividing line between Asian and Australian fauna in the Malay Archipelago. Weber's line is a line of supposed ‘faunal balance’ between the Oriental and the Australasian faunal regions within Wallacea. Wallacea consists of isolated islands that were never recently connected by dry land by continental land masses and thus were populated by species capable of crossing the straits between islands. Weber's line runs through this transitional area, at the tipping point between dominance by species of Asian versus Australian origin.