Flanked by the forbidding frozen wastes of the Arctic Ocean, Canada's last unknown frontier is under complex scientific scrutiny by a 70-man expedition - the Polar Continental Shelf Project. With international law ruling that countries claiming coastlines are also entitled to the potential resources of adjoining continental shelves - the shallow seas nearby - it was imperative at the beginning of the decade that Canada take inventory of its vast polar shelf regions, stake her claim through scientific knowledge. Now, after nine years of study, Canada has truly claimed its own - through the sustained efforts of scientists and technicians in one of the most inhospitable regions of the world. This year, after battling record March-April extremes of sub-zero cold combined with high winds, the arctic explorers are about the nation's business once more.