Causes of Glacial Ages
Any theory that attempts to explain the causes of glacial ages must successfully address two basic questions.First,what causes the onset of glacial conditions?For ice sheets to have formed,average temperatures must have been somewhat lower than at present and perhaps substantially lower than throughout much of geologic time. For that reason,a successful explanation would have to account for the gradual cooling that finally leads to glacial conditions.The second question is:What caused the alternation of glacial and interglacial stages that have been documented for the Pleistocene epoch (1.6 million to 10,000 years ago)?Whereas the first question deals with long-term trends in temperature that occur on a scale of millions of years,this second question relates to much shorter-term changes.
完整版题目和答案请付费后查阅
