نمونه سوالات آزمون های کارشناسی ارشد علوم زمین زبان عمومی و تخصصی (انگلیسی) امتحانات 94-86 - بخش (1)

Sea level all over the world swung in rhythm with the waxing and waxing of the ice sheets. When the ice sheets expanded, tens of millions of cubic miles of sea water were withdrawn to be iocked up on land as ice. Sea level was lowered as a consequence, perhaps by 40 or 50 fathoms (240 to 390 feet). This may not seem like much, but it was enough to profoundly alter world geography. Land areas, now separated, were then connected, and with the climatic stringencies of the time not only were migrations of whole populations of animals stimulated but they were made possible by the appearance of land bridges. Among these natural causeways are such links as the ones that connected Tasmania and Australia, Ceylon and India, New Guinea and Australia, and others that. united some of the islands of Indonesia. Most renowned of all was the land bridge joining Alaska and Siberia, now separated by the 55-meter-deep (180-foot-deep) waters of Bering Strait. In a way, this link must. have been a veritable freeway; with all sorts. of creatures, including human beings, pattering to and fro. Westbound from the New World, migrating into the Old,went the zebra, the camel, the. tapir, and the horse. Eastbound immigrants to this hemisphere were elk, musk ox, bison, elephant, mountain sheep; and mountain goat. Not the Ieast was man himself.