模仿文本： In the geological past, big events like the onset of Ice Ages or titanic volcanic eruptions and mass extinctions of animals and plants caused the planet to tip into new geological periods. All these upheavals left many traces in the rocks, forming at the Earth surfaces of those times. So are we leaving a similar trail of clues for posterity?

 

 

译文： 在过去的地质时期，冰河时期的降临抑或大型火山喷发，以及大量动植物的灭绝都是重大事件，它们令星球骤然进入新的地质时期。所有这些剧变都在当时地球表面的岩石构成上留下了许多印迹。那么我们是否也在为子孙后代留下类似的线索呢？