
Old Faithful is not only a spectacular sight;it’s also.a constant reminder that Yellowstone sits on one of the largest volcanoes in the world.If you’ve never heard of Yellowstone’s volcano,you’re not alone. 2 Yet it has erupted three times during the last 2 million years.And one of those eruptions spewed enough volcanic ash and other debris to blanket half the United States.
Yellowstone’s volcano is sometimes called a “supervolcano,” or extremely large and explosive caldera volcano. 3 .This supervolcano formed over a hot spot.an extremely hot area in Earth’s mantle.John Valley,a volcano professor,said that as the crust moves across a hot spot,the hot spot melts a section of the plate moving over it.Forming “one volcano after another.”
The Yellowstone hot spot melts thick continental crust,which may cause catastrophic
eruptions.According to experts the eruptions that created each of the three calderas in and around Yellowstone National Park were larger than any other volcanic eruption in recorded history.The most recent eruption,which happened 640,000 years ago,produced at least 1.000 cubic kilometers of ash and debris,which blanketed most of the western half of the United States. 4
Geological evidence shows Yellowstone has blown its stack every 700,000 years or so.“If nature were truly that regular and reliable,we would be due for another eruption soon,” said Valley “However,these processes are subject to variability, so we don’t really know when the next eruption will happen.”
5 It is the volcanic energy that powers the geysers and hot springs.creates the mountains and canyons.and generates the unique ecosystems that support Yellowstone’s diverse wildlife.
练习:
A. Three calderas make up more than a third Of Yellowstone National Park.
B. The first Yellowstone eruption,2 million years ago,released more than double that amount of ash and debris.
C.The volcano is so inconspicuous(不显眼的)that few people know it exists.
D.Then, an enormous fountain will shoot high into the air.
E.While the active geologist processes at Yellowstone do pose some risk to the public,they also make it a unique treasure.
F.Yellowstone National Park attracts the interest of geologists the world over
答案: D,C,A,B,E
2017年职称英语考试卫生类C级补全短文模拟及答案7.doc正在阅读:
2017年职称英语考试卫生类C级补全短文模拟及答案705-22
三年级作文有趣的含羞草300个字|三年级日记:有趣的含羞草_250字02-19
[四年级优秀数学日记600字]四年级优秀日记600字5篇05-19
2019秋季广东深圳市宝安区和平中英文实验学校诚聘心理健康教师公告03-04
2017年8月北京考点托福剩余考位查询01-21
简单现代儿童诗歌大全09-27
2017年社会工作者初级考试试题及答案:2017年北京社会工作者考试报名通知11-03
2022下半年江西小学教师资格证准考证打印时间及入口【10月25日-10月29日】10-27
2018江西省九江银行江西省县城客户经理招聘公告【55人】08-25