论文部分内容阅读
在统治地球1．4亿年的恐龙身上究竟发生了什么?大约六千六百万年前, 所有有关恐龙存在的迹象突然消失。发现恐龙大批的残骸后,我们继续寻找可以用来解释恐龙神秘绝迹的证据。加利佛尼亚大学地质学家渥尔特·爱尔瓦里兹可能已找到一个很有价值的线索。在搜集意大利古比奥附近的一个深谷的样品时,他看到一层标志着恐龙时代终结的不平常的粘土。这层粘土中有极高含量的铱,它是一种
What happened to the 140 million-year-old dinosaurs who rule the earth? Suddenly, all the signs of dinosaurs disappearing about 66 million years ago. After discovering the massive wreckage of dinosaurs, we continue to look for evidence that can be used to explain the mysterious extinction of dinosaurs. The University of California geologist Walter Alvarez may have found a very valuable clue. While collecting a sample of deep valleys near Gubbio, Italy, he saw an unusual layer of clay that marked the end of the dinosaurs. This layer of clay has a very high content of iridium, which is one