Mighty Glaciers

Mighty Glaciers written by Ned Jensen

《强大的冰川》 作者：内德·延森

Introduction. The earth's surface constantly changes. Wind, water, and heat wear down mountains and crack stone. But some of the most dramatic changes are caused by giant pieces of ice and rock called glaciers. Glaciers move slowly over the land. They carve out cliffs, valleys, and prairies as they go. When glaciers melt, they leave behind lakes, rivers, and hills of soil and boulders.

引言 地球的表面一直在不断变化 风、水和热量会侵蚀山脉，使岩石开裂 但一些最惊人的变化是由叫做冰川的巨大冰岩块造成的 冰川在陆地上缓慢移动 它们一路雕刻出悬崖、山谷和草原 冰川融化时，会留下湖泊、河流还有由土壤和砾石堆成的小山

Types of glaciers. Two common types of glaciers are continental glaciers and valley glaciers. Continental glaciers form at the north and south poles of the Earth. These huge sheets of ice cover vast stretches of land. Continental glaciers can be so thick that only the tops of mountains stick out above them. Much of Greenland and Antarctica are buried beneath continental glaciers.

冰川的种类 两种常见的冰川是大陆冰川和山谷冰川 大陆冰川形成于地球的南北两极 这些巨大的冰盖覆盖了大片陆地 大陆冰川非常厚，只有山顶能从冰面露出来 格陵兰岛和南极洲的大部分地区都被埋在大陆冰川之下

Valley glaciers form on high mountains that rise above the snow line. Above the snow line, snow covers the ground all year. Even in the tropics, valley glaciers can form on the tallest peaks. Like rivers of ice, valley glaciers move through long, narrow valleys.

山谷冰川形成于雪线以上的高山上 在雪线以上，积雪常年覆盖地面 即使在热带地区，最高的山峰上也能形成山谷冰川 山谷冰川就像冰做的河流，在狭长的山谷中流动

How do glaciers grow? In some places, the temperature stays below freezing for most of the year. Snow piles up much faster than it melts. Each new layer of snow presses down on the snow beneath it. The lower layers of snow become squashed or compressed.

冰川是怎么形成的？ 有些地方的温度一年中大部分时间都保持在冰点以下 积雪堆积的速度远远快于融化的速度 每一层新的积雪都会挤压下方的积雪 下层的积雪就会被挤压、压实

The compressed snowflakes become ice crystals called fern. The fern crystals squash together as more and more snow presses down on them. Eventually the fern turns into a huge slab of ice known as a glacier.

被压实的雪花会形成叫做粒雪的冰晶 随着越来越多的积雪压在上面，粒雪冰晶挤压在一起 最终粒雪会变成巨大的冰块，也就是我们所说的冰川