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Polunin: Biological Conservation in the Arctic POLUNIN, NICHOLAS (1953). The real Arctic. Proc. Seventh hit. Bot. Congr., Stockholm, 1950, pp. 611-12.
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POLUNIN, NICHOLAS (1959). Circumpolar Arctic Flora. Clarendon Press, Oxford, and Oxford University Press, London, etc., xxviii + 514 pp., illustr. POLUNIN, NICHOLAS(1960). Introduction to Plant Geography and Some Related Sciences. Longmans, Green, London etc., and McGraw-Hill, New York, xix q coloured map + 640 pp., illustr. POLUNIN, NICnOLAS (1961). Arctic flora. Pp. 59-63 in Encyclopedia o f the Biological Sciences, Ed. Peter H. Gray. Reinhold, New York, xxi + 1119 pp. POLUNIN, NICHOLAS(1969). Aspects of botanical conservation. X I International Botanical Congress, Seattle, Washington: Abstracts of the papers presented, p. 172. POLUN1N, NICHOLAS(MS). Plant Sciences in the Arctic and Subarctic. Volume I: Arctic Plant Exploration, Taxonomy, and Geography. Clarendon Press, Oxford, and Oxford University Press, London, etc. (in preparation). PORSILD, A. E. (1957). Illustrated Flora o f the Canadian Arctic Archipelago. National Museum of Canada Bulletin No. 146 (Biological Series No. 50), iii + 209 pp., illustr. PORSILD, MORXEN P. (1930). Stray contributions to the flora of Greenland I-V. Medd. om Gronland, 77, 1-44. PORSILD, MORTEN P. (1932). Alien plants and apophytes of Greenland. Medd. om Gronland, 92(1), 1-85 + map.
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Conservation on the Moon
time that a rock, brought freshly to the surface by a large meteoric impact, can be expected to remain near the surface before it is either ground to powder by numerous small meteoric impacts or is buried again by a large impact near by. The astronauts left their mark on the Moon in several ways, most notably by the waste materials they left behind - - t h e descent stage, life-support systems, and other apparatus. However, it is interesting to contemplate that even their footprints, clearly embedded in the lunar soil,* may still be discernible tens of millions of years from now. After 100 million years or so, the hardware left on the lunar surface will presumably have been beaten into trash by meteoric impact, and aluminum fragments (perhaps resembling beer cans) distributed on and in the lunar soil may be the clearest visible evidence remaining of Man's first visit to the Moon. In any case there now seems no possibility whatever of any form of life existing on the Moon.
The early reports on materials brought back from the Moon by Armstrong and Aldrin in the Apollo 11 operation show that lunar rocks erode and break down into fine material. The basic rocks in the Apollo 11 landing area are apparently basaltic in nature, not unlike many basalts on earth, though darker in colour as a result of a higher titanium content. These crystalline rocks on the lunar surface have been extensively broken into small fragments by meteoric bombardment. Most of the impacts are by very small meteorites, and the predominant fragments are therefore also small, resulting in an abundance of rock powder. The lunar surface would probably be covered solely by fine powder were it not for the occasional impacts by larger meteorites which break out larger fragments of solid crystalline rock from greater depths and bring some of them to the surface, where they undergo slow erosion to fine powder by the more numerous impacts of small meteorites. Apparently glass is produced in the meteoric impacts by the melting of some of the surface material. Much glass is found in the powdered material, either in the form of small spheres (droplets) or as surface deposits probably formed by the splashing of liquid droplets on the surface. The length of time that crystalline rocks on the lunar surface have been there can be estimated from cosmic rayinduced changes in the rocks, the published result indicating about 100 million years. This is, then, about the length of
SORENSEN, THORV (1933). The vascular plants of East Greenland from 71000 ' to 73°30 ' N. Lat. Medd. om Gronland, 101(3), 1-177 pp. and additional plates. TOLMAXCHEV, A. I. et al. (1960-). Flora Arctica URSS. Akedemia N a u k URSS, Moscow-Leningrad. [It should be noted, however, that the area accepted in this important work as arctic is much more extensive than in our own conception, while the species delimitation is often different.] WENDELBO, PER (1959). Primula scandinavica in the arctic islands of the European USSR. Nytt Mag. for Botanikk, 7, 157-9.
WENDLAND,WAYNE M. & BRYSON,RE|D A. (1970). Atmospheric dustiness, Man, and climatic change. Biol. Conserv., 2(2), 125-8, illustr. WIGGINS, IRA L. & THOMAS, JOHN H. (1962). A Flora o f the Alaskan Arctic Slope. Arctic Institute of North America Special Publication No. 4. University of Toronto Press, Toronto, ix + 425, illustr. WURSXER, CHARLESF., Jr (1969). Chlorinated hydrocarbon insecticides and the world ecosystem. Biol. Conserv., 1(2), 123-9.
FRANCIS S. JOHNSON, Acting President, University o f Texas at Dallas, Box 30365, Dallas, Texas 75320, USA.
" See the illustrated note on page 178 of this issue--Ed.