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Unformatted text preview: s change the meaning in important ways or leave out essential information. ○One explanation notes that green icebergs stand out among other icebergs under a great variety of light conditions, but this is attributed to an optical illusion. ○One explanation for the color of green icebergs attributes their color to an optical illusion that occurs when the light from a nearhorizon red Sun shines on a blue iceberg. ○One explanation for green icebergs attributes their color to a great variety of light conditions, but green icebergs stand out best among other icebergs when illuminated by a nearhorizon red Sun. ○One explanation attributes the color of green icebergs to an optical illusion under special light conditions, but green icebergs appear distinct from other icebergs under a great variety of light conditions.
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Paragraph 4: The ice shelf cores, with a total length of 215 meters (705 feet), were long enough to penetrate through glacial ice—which is formed from the compaction of snow and contains air bubbles—and to continue into the clear, bubblefree ice formed from seawater that freezes onto the bottom of the glacial ice. The properties of this clear sea ice were very similar to the ice from the green iceberg. The scientists concluded that green icebergs form when a twolayer block of shelf ice breaks away and capsizes (turns upside down), exposing the bubblefree shelf ice that was formed from seawater.
4. The word penetrate in the passage is closest in meaning to ○collect
5. According to paragraph 4, how is glacial ice formed? ○By the compaction of snow
○By the freezing of seawater on the bottom of ice shelves
○By breaking away from the ice shelf
○By the capsizing of a twolayer block of shelf ice
6. According to paragraph 4, ice shelf cores helped scientists explain the formation of green icebergs by showing that ○the ice at the bottom of green icebergs is bubblefree ice formed from frozen seawater
○bubblefree ice is found at the top of the ice shelf
○glacial ice is lighter and floats better than sea ice
○the clear sea ice at the bottom of the ice shelf is similar to ice from a green iceberg
Paragraph 5: A green iceberg that stranded just west of the Amery Ice Shelf showed two distinct layers: bubbly bluewhite ice and bubblefree green ice separated by a onemeterlong ice layer containing sediments. The green ice portion was textured by seawater erosion. Where cracks were present, the color was light green because of light scattering; where no cracks were present, the color was dark green. No air bubbles were present in the green ice, suggesting that the ice was not formed from the compression of snow but instead from the freezing of seawater. Large concentrations of singlecelled organisms with green pigments (coloring substances) occur along the edges of the ice shelves in this region, and the seawat...
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- Fall '13