Wallace Line by the Sahul Shelf to New Guinea. The biogeographic boundary known as Lydekker's Line, which separates the eastern edge of Wallacea from the Australian region, has a similar origin to the Wallace line. During ice age glacial advances, when the , both Asia and Australia were united with what are now islands on their respective continental shelves as continuous land masses, but the deep water between those two large continental shelf areas was, for over 50 million years, a barrier that kept the flora and fauna of Australia separated from those of Asia. Wallacea consists of islands that were not
Blakiston's Line in his honor on Mount Hakodate. Blakiston's Line The Blakiston Line or Blakiston's Line is a faunal boundary line drawn between two of the four largest islands of Japan: Hokkaidō in the north and Honshū, south of it. It can be compared with faunal boundary lines like the Wallace Line. Certain animal species can only be found north of Blakiston's Line, while certain other species can only be found south of it. Thomas Blakiston, who lived in Japan from 1861 to 1884 and who spent much of that time in Hakodate, Hokkaido, was the first person to notice that animals