Sleeping Giant

Right now, an eruption is brewing in Yellowstone National Park. Sometime during the next two hours, the park’s most famous geyser, Old Faithful, will begin gurgling boiling water and steam. 1

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 so1. “If nature were truly that regular and reliable, we would be due for another eruption soon,2” 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 Yellow tone’s diverse wildlife3. 词汇： brew /bru:/ n.酝酿 crust /krQst/ n.地壳 Yellowstone National Park黄石国家公园 mantle /5mAntl/ n.地幔 geyser /5^aizE/ n.间歇泉 continental /　　　　　　　　　　　　 / adj.大陆的 gurgle /5^E:^l/ v.汩汩地流 catastrophic /9kAtE`strCfIk/ adj.灾难的 spew /spju:/ v.喷涌 variability /　　　　　　　　　　　　　　 / n.可变性 caldera /kAl5diErE/ n.火山口洼地 canyon /5kAnjEn/ n.峡谷注释：

1. every 700,000 years or so：每 70万年左右

2. If nature were truly that regular and reliable, we would be due for another eruption soon：如果自然界真的如此有规律，如此可靠，那么，我们将很快面临另一次火山喷发。这是一个虚拟句。注意从句中的动词用了 were，不是 is或 was，主句中用了 would be，不是 will be。

3. 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：这是一句用了 it is … that结构的强调句。被

强调的内容放在 it is和 that之间。本句被强调的是 the volcanic energy。被强调前的句子是： The volcanic energy 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 geological 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.

答案与题解：

1. D 第一段第二句说，在随后的两个小时的某一时刻，间歇泉会涌出沸水和蒸汽。后续句应该是选项 D。boiling water变成 fountain, shoot high into the air。

2. C 第二段第二句说，如果你不知道黄石公园的下面是火山，没有关系，很多人都不知道。为什么会如此呢? C道出了原因。所以， C是答案。

3. A 第三段第一句说黄石公园的火山 extremely large，所以有时候被称为 supervolcano。选项 A的句子具体说明这个 supervolcano大到什么程度，所以是答案。

4. B 在选项 B的 more than double that amount of ash and debris这个短语中，有关键词 double that amount，说明前面句子一定有一个数字。检查后 .发现这个数字是“ 1,000 cubic kilometers of ash and debris”，可以断定，选项 B的句子就是要放回原位的句子。

5. E “空 5”所在段的前面两段介绍了黄石公园火山以前喷发时的可怕情景。“空 5”所在段叙述火山能量带来的好处。这是两种情景截然相反的描写，中间很可能有一句过渡句，把它们连接起来。选项 E就是过渡句，应该是本题的答案。