Macquarie Island (54°30'5, l 59°00'E) is an emergent part of the Macquarie Ridge Complex composed of ocean-floor rocks of Miocene age now 4000 m above the ocean floor. A number oflandforms, including palaeobeaches now above sea level (a.s.l.)on Macquarie Island, were formed by marine erosion during uplift of the island. During the last Pleistocene period oflow sea level (c. 20 ka) the island was three times larger than now. Thermoluminescence (TL) dating of two palaeobeaches indicates Pleistocene ages: 172 ± 40 ka for one at 100 m a.s.l. and 340 ± 80 ka for another at 263 m a.s.l. Matching the altitude sequence of palaeobeaches on Macquarie Island with the pattern of peaks in world sea level determined from deep sea cores allows an independent estimate of beach ages. Comparison of the altitude and sea level sequences most plausibly places the 100 m palaeobeach in Oxygen Isotope Stage Se (130-125 ka) and the 263 m palaeobeach in Stage 9 (340-330 ka), matching reasonably with the TL dates. Other palaeobeaches at about 50 m and 170-190 m a.s.l. then correlate with high sea levels. We calculate an average rate of uplift for the island of0.8 mma-1 • At this rate, 4000 m of Macquarie Ridge uplift would have taken about five million years and the top of the island may fi rst have emerged some 700 to 600 ka. During the six Pleistocene glacial interglacial cycles since then, there has been periglacial rather than glacial activity on cold uplands, but conditions suitable for vegetation of the present type persisted close to sea level.

Sub-Antarctic land is a rare resource in world terms. It is appropriate to recognise the sub-Antarctic as a region distinct f r om the cool temperate zone to its north and the Antarctic zone to its south, a region with its own characteristics, and with significant intrinsic value and scientific importance. Appropriate protection from anthropogenic change and exploitation must be ensured for the sub-Antarctic.

Feld mark vegetation occurs extensively on the plateau of Macquarie island above about 200 m. Alternating stripes of vegetation and gravel are frequently associated with terraced terrain. Detailed study of 38 terraced sites with non-windward aspects shows vegetation-terrace interaction to be active under present climatic conditions. Wind, moisture, hillslope, slope stability and vegetation all affect terrace form.

Macquarie Island lies close to, but on the eastern side of the boundary between the eastern (Pacific) and western (India-Australia) limbs of the Southern Oscillation. Its temperature record matches that of the area east and southeast of New Zealand, rather than Tasmania. Temperature is inlluenced by atmospheric pressures in the Southern Ocean to the east and west, which can result in a warm northeasterly or cold southerly airllow over the island. It is a sensitive indicator of climatic trends because of its location at high latitude in a longitudinal region of frequent ridge formation and blocking in the Southern Hemisphere circulation. Temperature records for Macquarie Island (1949-86) show a l°C warming trend (twice the global average), accelerating in the last 20 years with eight of the ten warmest years occurring in the last decade. The greatest average rate of warming has occurred in late summer and early autumn and the lowest in spring. In severe ENSO years the island cools. The warming is marked, in relation to the annual mean (4.8°C), and the biological effects should be considered.

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