GRE阅读理解真题练习-智课教育旗下智课教育.pdfVIP

智 课 网 G R E 备 考 资 料 GRE阅读理解真题练习-智课教育旗下智课教育 GRE阅读理解真题练习，附有相关的参考答案，给大家参考。 The term “Ice Age” may give a wrong impression. The epoch that geologists know as the Pleistocene and that spanned the 1.5 to 2.0 million years prior to the current geologic epoch was not one long continuous glaciation, but a period of oscillating climate with ice advances punctuated by times of interglacial climate not very different from the climate experienced now. Ice sheets that derived from an ice cap (ice cap: n. 〈地〉冰帽;冰冠a cover of perennial ice and snow; specifically: a glacier forming on an extensive area of relatively level land and flowing outward from its center) centered on northern Scandinavia reached southward to Central Europe. And Beyond the margins of the ice sheets, climatic oscillations affected most of the rest of the world; for example, in the deserts, periods of wetter conditions (pluvials) contrasted with drier, interpluvial periods. Although the time involved is so short, about 0.04 percent of the total age of the Earth, the amount of attention devoted to the Pleistocene has been incredibly large, probably because of its immediacy, and because the epoch largely coincides with the appearance on Earth of humans and their immediate ancestors. There is no reliable way of dating much of the Ice Age. Geological dates are usually obtained by using the rates of decay of various radioactive elements found in minerals. Some of these rates are suitable for very old rocks but involve increasing errors when used for young rocks; others are suitable for very young rocks and errors increase rapidly in older rocks. Most of the Ice Age spans a period of time for which no element has an appropriate decay rate. Nevertheless, researchers of the Pleistocene epoch have developed all sorts of (all sorts of:各种各样的) more or less fanciful model schemes of how they would have arranged the Ice Age had they been in charge of events. For example, an early classification of Alpine glaciation suggested