2 The Mid-Atlantic Ridge is a submarine ridge that belts the earth along the middle of the ocean floor from the Arctic to the Antarctic. In only one place on its route, however, does the ridge heave itself out of the ocean. That place is Iceland, and its location explains why Iceland has so many volcanic eruptions. The country is situated smack in the middle of the serpent's course. And wherever the serpent twitches, the earth convulses – the ocean explodes and fire is spit into the sky.
3 This is why: The earth is a sphere made up of layers. The top layer is the crust, where life occurs. Humans, animals, plants live here. Not all of the crust is visible, however; some of it is covered with oceans and soil. The crust, scientists have learned, is not just one whole chunk. Similar to a jigsaw puzzle, it is made up of pieces called plates. The layer beneath the crust is the mantle. The mantle is made up of hot rock, and nothing can live there.
4 Hot rock is also called molten rock, or magma, and it can flow like hot tar. Although it is hard to imagine, the crust where we live actually floats on this deep, deep sea of molten hot rock. The plates of the crust then sail about like little ships on a sea of tar. They do not sail quickly – just a few inches every year–and their cargo is whatever is on top of them – oceans, islands, or even entire continents.
5 In places called rifts the plates tear apart from each other. Then molten rock in the mantle sometimes squishes out of the rift. Over hundreds of thousands of years, molten rock, welling up from the rifts under the sea, has hardened into a series of ridges. These ridges run like a belt, a seam, or, some might say, a serpent across the floor of the earth's ocean all around the globe. In the Mid-Atlantic Ridge the plates move apart. In the mid-ocean ridge of the Pacific the plates collide, with one sliding under another. Whether the plates pull apart or collide, the result is the same – magma from the earth's mantle wells up, causing volcanic eruptions and adding mass to the trailing edges of the plates.
6 Such volcanic activity – both beneath the surface of the sea and on dry land – has been recorded from the time the Viking sailors plied the icy waters in their slender dragon ships, more than a thousand years ago. In the 10,000 to 15,000 years since the last ice age, more than 150 volcanoes have been active in Iceland. Lava covers nearly one-tenth of the country's surface. As far back as the sixth century, Irish monks who found their way to Iceland in leather boats described flames leaping from the sea, which could only be the fires of submarine volcanic eruptions.
7 In Iceland everyone – including scientists – knows the sagas, the stories of their ancestors.
These tales of the violence and the turmoil of the Norsemen's world, their warlike gods, their
giant beasts that spit fire, seem to fit the geologic turmoil of the land. Although scientists know it
is a ridge, they often call it a serpent, and they are alert to every wiggle: they know that when the
serpent twitches extraordinary events can happen.
From SURSTEY: THE NEWEST PLACE ON EARTH by Kathryn Lasky;
photographs by Christopher G. Knight. Copyright © 1992 by Kathryn Lasky.
Reprinted by permission of Hyperion Books for Children.
A. instruct the reader about how to locate the Mid-Atlantic Ridge on a map.
B. persuade the reader that the Midgard Serpent is the Mid-Atlantic Ridge.
C. entertain the reader with stories, myths, and legends.
D. inform the reader about the Mid-Atlantic Ridge.
A. the ocean surging up on the land
B. the Midgard Serpent flying into a rage
C. the plates of earth's crust tearing apart from each other
D. the molten rock flowing into the water
|
belt: v 1. to encircle or fasten with a
belt.
2. to beat with or as if with a belt. 3. to sing in a forceful manner or style. 4. to move or act in a speedy, vigorous, or violent manner. |
Which definition most closely matches the meaning of belts as it is used in paragraph 2?
A. definition 1
B. definition 2
C. definition 3
D. definition 4
A. hit.
B. separate.
C. sink.
D. rise.
A. noun
B. pronoun
C. adjective
D. adverb
A. the sun's reflection on the ocean surface.
B. eruptions from distant Iceland.
C. underwater volcanoes exploding above the water's surface.
D. rafts of molten lava floating on the sea.
A. location of the Mid-Atlantic Ridge.
B. formation of Iceland.
C. layers of the earth in order.
D. results of plate movement in the crust.
A. It provides a visual image for what the author is describing.
B. It suggests some of the dangers of earth's crust.
C. It makes it seem as if earth's crust is an ocean.
D. It shows that magma is hot.