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
Line of beauty Line of beauty Line of beauty is a term and a theory in art or aesthetics used to describe an S-shaped curved line (a serpentine line) appearing within an object, as the boundary line of an object, or as a virtual boundary line formed by the composition of several objects. This theory originated with William Hogarth (18th-century English painter, satirist, and writer), and is an essential part of Hogarth's theory of aesthetics as described in his "Analysis of Beauty" (1753). According to this theory, S-shaped curved lines signify liveliness and activity and excite the attention of the viewer as contrasted