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知道了早期落基山脉下降的原因，会带给我们怎么样的启示？落基山脉经过了侵蚀后，接下来的火山作用又带给了这座山什么样的变化呢？经历了侵蚀和火山作用，落基山脉还会经历什么呢？值得期待！
This fine-grained ash suggests huge volcanic eruptions nearby. They spewed out（喷射） thick clouds of hot air, ash and volcanic rock which settled on the ground. Radiocarbon（ [核] 放射性碳）dating the rock revealed that it happened 25 million years ago.
"Ash was deposited as it came out of the sky as plumes（羽毛）. Most of it came from the West and was deposited in the basins across Wyoming."
After the lower Rockies were buried by their own rock, volcanic ash settled on top and covered the area with a thick white sheet.
"At the time of the deepest basin filled with this volcanic material, all you would see in this area was the very tops of the peaks exposed, the rest would be large extensive lateral ash sheets."
Erosion and volcanism（n. [地质] 火山作用） completely transformed the terrain and buried the Rockies. But then, over millions of years, rivers flushed out the eroded rock.
Most of it is thought to have ended up in the Missouri and Mississippi Rivers, from where it was transported into the sea. What's left are the mountains we see today. This also confirmed the theory geologists had about the formation of Wind River Canyon, the incredible amount of infield （耕地）buried the Owl Creek Mountains. Wind River flowed on top and began carving into the mountains, creating the canyon we see today.
The investigation into what happened to the early Rocky Mountains reveals two major clues. Granite, found on the Pumpkin Buttes, is evidence that the early Rockies dumped their eroded rock into the basins. Wind River Canyon, cutting straight through the Owl Creek Mountains is evidence that the Rockies were buried by their own debris. The once mighty Rockies had now been cut down to nearly half their original size, but the story was far from over. Before they became the mountains we know today, they would have to endure an even greater assault.
小编有约：早期落基山脉的变迁史让人着迷，就如同一位沧桑的老人，它的故事给Daisy的感觉就是你不探索则以，如果开始听了，就会坚持听下去，然后悟出自己的道理，一切事物都有自己的衰荣史，最开始从海底升起来，到慢慢的经历毁灭性的打击，一直保存到我们现在看到的山，虽然高度已减少一半，但是它依然在这个世界存在着，好多人遭受到了打击，选择一条不归路。当然这只是小编的意见，欢迎大家各抒己见。
课后题目：这次Daisy想要问问大家有仔细听吗？对于早期落基山脉历史变迁的调查，结果揭示出了两个主要线索。能告诉Daisy是哪两个主要线索吗? 可以用自己的话来表述，只要意思差不多就行哦。
