Sea before the break-up of Gondwana. These four structures have similar crustal thickness and underwent the same pre-break-up process of crustal thinning and underplating during the Early Cretaceous or Jurassic. The southern margin of the plateau was located next to the continental shelves of the eastern Ross Sea and Marie Byrd Land. There are two systems of magnetic anomalies on the Campbell Plateau: the Stokes Magnetic Anomaly System (SMAS) and the Campbell Magnetic Anomaly System (CMAS). The origin and relationship of these anomalies remain unclear. Biogeology The islands are important breeding centres for both endemic and circumpolar species, including the royal albatross, crested penguin, and Hooker's sea lion. The southern part of South Island (Fiordland, Southland and Otago) can be considered part of the Campbell Plateau, both biologically and geologically. Endemic taxa include the spider genus Gohia, the frog species Puhuruhuru patersoni, and nine genera of beetles. The order Lepidoptera (moths and butterflies) also link the southern South Island to the New Zealand Subantarctic Islands. Macquarie Island is biologically but not geologically related to the Campbell Plateau. The island is made of oceanic crust that formed at the Macquarie Triple Junction. This triple junction was originally located adjacent to the Campbell Plateau but is now isolated south of it due to sea floor spreading. The plateau and the island share several endemic taxa, including six beetle species, a fly genus (Schoenophilus) and a vascular plant genus (Pleurophyllum). Further support for this connection comes from the aralia genus Stilbocarpa and possibly the cormorant. Oceanography South of the Campbell Plateau, the eastward-flowing Antarctic Circumpolar Current (ACC) is bounded by the Antarctic Polar Front (APF) and the Subantarctic Front (SAF). It reaches New Zealand with an average volume of c. 130×106 m3/s. South of New Zealand it is partly deflected in the Tasman Sea as a broad, weak flow. The main part of the ACC, however, passes around the Macquarie Ridge together with the SAF and then flows north along the eastern margin of the Campbell Plateau. At 55°S and 50°S the ACC turns eastward again. There is, however, a wind-driven Ekman transport of surface water across the Campbell Plateau. At the Subtropical Convergence the Southland Current rounds the South Island and flows north-east along the island's east coast. From there it entrains Subantarctic and subtropical waters across the north-western Campbell Plateau before branching over the Chatman Rise north of the plateau. References