Icebergs are among natures most spectacular creations, and yet most people have never seen one. A vague air of mystery envelops them. They come into being ----- somewhere ------in faraway, frigid waters, amid thunderous noise and splashing turbulence, which in most cases no one hears or sees. They exist only a short time and then slowly waste away just as unnoticed.
Objects of sheerest beauty they have been called. Appearing in an endless variety of shapes, they may be dazzlingly white, or they may be glassy blue, green or purple, tinted faintly of in darker hues. They are graceful, stately, inspiring ----- in calm, sunlight seas.
But they are also called frightening and dangerous, and that they are ---- in the night, in the fog, and in storms. Even in clear weather one is wise to stay a safe distance away from them. Most of their bulk is hidden below the water, so their underwater parts may extend out far beyond the visible top. Also, they may roll over unexpectedly, churning the waters around them.
Icebergs are parts of glaciers that break off, drift into the water, float about awhile, and finally melt. Icebergs afloat today are made of snowflakes that have fallen over long ages of time. They embody snows that drifted down hundreds, or many thousands, or in some cases maybe a million years ago. The snows fell in polar regions and on cold mountains, where they melted only a little or not at all, and so collected to great depths over the years and centuries.
As each years snow accumulation lay on the surface, evaporation and melting caused the snowflakes slowly to lose their feathery points and become tiny grains of ice. When new snow fell on top of the old, it too turned to icy grains. So blankets of snow and ice grains mounted layer upon layer and were of such great thickness that the weight of the upper layers compressed the lower ones. With time and pressure from above, the many small ice grains joined and changed to larger crystals, and eventually the deeper crystals merged into a solid mass of ice.
2017届高考英语一轮复习高考题型提能练:2(北师大版含答案)
2017届高考英语一轮复习专题强化训练:专题2 形容词、副词、介词和介词短语(含解析)
2017届高考英语一轮全册复习学案:Unit11《The Media》(北师大版)
2017届高考英语一轮复习专题强化训练:专题2 阅读理解 第1讲专题强化训练(含解析)
2017届高考英语一轮复习高考题型提能练:12(北师大版含答案)
2017届高考英语一轮复习高考题型提能练:23(北师大版含答案)
2017届高考英语一轮复习高考题型提能练:9(北师大版含答案)
2017届高考英语一轮复习专题强化训练:专题2 阅读理解 第3讲专题强化训练(含解析)
2017届高考英语一轮复习高考题型提能练:6(北师大版含答案)
2017届高考英语一轮复习高考题型提能练:22(北师大版含答案)
2017届高考英语一轮复习语法专项突破配套学案:第10讲 名词性从句(北师大版)
2017届高考英语一轮复习高考题型提能练:4(北师大版含答案)
2017届高考英语一轮全册复习学案:Unit7《The Sea》(北师大版)
2017届高考英语一轮复习专题强化训练:专题2 阅读理解 第1讲跟踪训练(含解析)
2017届高考英语一轮复习专题强化训练:专题2 阅读理解 第4讲跟踪训练(含解析)
2017届高考英语一轮全册复习学案:Unit6《Design》(北师大版)
2017届高考英语一轮复习高考题型提能练:19(北师大版含答案)
2017届高考英语一轮复习语法专项突破配套学案:第9讲 定语从句(北师大版)
2017届高考英语一轮复习高考题型提能练:8(北师大版含答案)
2017届高考英语一轮复习专题强化训练:专题2 阅读理解 第3讲跟踪训练(含解析)
2017届高考英语一轮复习专题强化训练:专题2 阅读理解 第2讲跟踪训练(含解析)
2017届高考英语一轮全册复习学案:Unit13《People》(北师大版)
2017届高考英语一轮复习语法专项突破配套学案:第2讲 名词和冠词(北师大版)
2017届高考英语一轮复习语法专项突破配套学案:第3讲 代词和数词(北师大版)
2017届高考英语一轮复习专题强化训练:专题2 阅读理解 第2讲专题强化训练(含解析)
2017届高考英语一轮复习语法专项突破配套学案:第6讲 时态和语态(北师大版)
2017届高考英语一轮复习语法专项突破配套学案:第8讲 连词和状语从句(北师大版)
2017届高考英语一轮复习演练:5.3《Adventure in Literature and the Cinema》(外研版含解析)
2017届高考英语一轮复习高考题型提能练:3(北师大版含答案)
2017届高考英语一轮复习高考题型提能练:7(北师大版含答案)