Wallace Line Line. Wallace Line The Wallace Line or Wallace's Line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by English biologist Thomas Henry Huxley, that separates the ecozones of Asia and Wallacea, a transitional zone between Asia and Australia. West of the line are found organisms related to Asiatic species; to the east, a mixture of species of Asian and Australian origin is present. Wallace noticed this clear division during his travels through the East Indies in the 19th century. The line runs through Indonesia, between Borneo and Sulawesi (Celebes), and through
Sunda Shelf these areas of the Asian continental shelf that were exposed during the last ice age. Sundaland included the Malay Peninsula on the Asian mainland, as well as the large islands of Borneo, Java, and Sumatra and their surrounding islands. The same steep undersea gradients that mark the eastern boundary of Sundaland are identified biogeographically by the Wallace Line, identified by Alfred Russel Wallace, which marks the eastern boundary of Asia's land mammal fauna, and is the boundary of the Indomalaya and Australasia ecozones. The shelf has resulted from millennia of volcanic activity and erosion of the Asian continental mass, and