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建立人际资源圈Ice_Age
2013-11-13 来源: 类别: 更多范文
Ice Age
ABSTRACT
This paper is an overview of the more popular theories for the occurrence of ice ages. No consensus has been reached to definitely explain the causes for ice ages, but four theories are detailed here. Reduction of CO2, volcanoes, continental changes, and earths orbital changes are theories that will be discussed. There are many more theories that could be described, however many of these theories lacked support. The ideas discussed here are all backed by some degree of scientific evidence and thus deserve consideration.
INTRODUCTION
Since mans initial curiosity about the history of his earth, much has been discovered about the way the earth moves and changes, including its climate. Scientists have found geologic evidence of at least five ice ages. The first seemed to occur more than two billion years ago and the most recent peeked just 18,000 years ago (Hughes 1993, pg. 11). However, there is one mystery that has seemed to elude scientists from all over the world for quite some time. This mystery is the cause of the several eras of ice that have appeared many times throughout earths history. There have been numerous theories formulated to
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