冰川时期英文

冰川期 glacial age，ice age，glacial period 这是指地球气候酷寒，高纬度地方的广阔区域为大陆冰川（continental glacier）所覆盖的时期。冰川的发生是极地或高山地区沿地面运动的巨大冰体。由降落在雪线以上的大量积雪，在重力和巨大压力下形成，冰川从源头处得到大量的冰补给，而这些冰融化得很慢，冰川本身就发育得又宽又深，往下流到高温处，冰补给少了，冰川也愈来愈小，直到冰的融化量和上游的补给量互相抵消。一般冰川为舌状，冰川面往往高低不平，有的地方有深的裂口，即冰隙。冰川可分为大陆冰川和山岳冰川两大类

这是指地球气候酷寒，高纬度地方的广阔区域为大陆冰川（continental glacier）所覆盖的时期。最近的冰川期在更新世，据在欧洲和北美研究的结果，认为共有六次冰川期，五次间冰川期。在日本根据分析冰斗地形（围谷地形，kar）地形发现有两次冰川期。最显著的冰川期是在石炭纪一二迭纪，冰川的遗迹残留于冈瓦纳大陆。除上述两大冰川期外，在欧洲和美洲还发现有前寒武纪、中生代和第三纪的冰川遗迹，但都不太显著。冰川时代在地质史上，冰川曾多次滑过地球表面，冲击刻画过大地，形成许多湖泊和沼泽。最近的一次冰河时代发生在大约20亿年前。在加拿大南部，从东向西绵延1000英里的地面上，有一系列原始冰川的沉积物。这块最早的加拿大冰原，想必至少有1000英里长、1000英里宽，数千英尺厚。最新的证据表明冰块曾流到美国北部，至少进入了米歇根地区。科学家们认为在南非、印度中部和澳洲西部发现的冰河沉积物与加拿大南部的冰河沉积物属于同一个时代。如果是这样，那么20亿年前的冰河时期想必非常广泛，并且延续了数百万年。从那以后，地球经历过若干次冰河时期。大约在后10亿年当中，地球至少经历过6个主要冰河时期，每次发生的间隔大约为1.5亿年，每次都持续大约5000万年。至于为什么要有这种周期性的冰河时代，这是地球史的难解之谜。科学家们提出不少有关这方面的理论，从洋流的改变到太阳黑子的周期变化等，五花八门，不一而足。但是没有哪一种理论站得住脚，令人信服。很明显，冰河现象是多种因素造成的，但有一点看来是肯定的，地球目前仍然处于冰河时代。冰川期这个说法可能有些含糊不清。通常这一说法指的是地球上部分地区被冰川覆盖了一二百万年的那个时期。这些时代通常以一系列冰川前进或间冰期（冰川停止前进、溶化、后退）为标志。但是，地质学家所说冰河时代是指全球变冷的那段时间，可能延续了几百万年。前面提到的5000万年的那个时代被认为是冰河时代。很明显，在一个冰河时代里可能、也确实发生过几个冰川期。最近这次冰河时代大约在6500万年前开始，好像刚巧与白垩纪的大灭绝联系在一起。大量的证据表明地球曾与巨大的彗星或小行星相撞，后者的残余部分飞向外层空间，撞击造成的森林大火发出的大量烟尘弥漫了大气层的低层，挡住了阳光，结果使地球的温度急剧下降，并产生大量酸雨。这样，仅存的恐龙灭绝了，3/4现有植物和动物物种死光了。这次相撞还可能多少改变了一下地球的运行轨道，这就是为什么地球总保持这种温度较低的状态，而且没有任何迹象表明地球可能恢复到中生代适于恐龙生长的较热的气候。冰河时代的开始是个缓慢的过程。大约在6500万年前南极开始形成冰川，冰面越来越大、变小、又扩大，逐渐形成厚厚的隆起的冰原。大约到2000万年前，冰面覆盖了整个南极大陆，这个过程现在仍在继续。大约到1200万年前，冰川才开始扩散、移动，并覆盖了阿拉斯加山区。在冰河时代，格陵兰冰川比较年轻，因为这块大陆直到大约300万年前才被冰川覆盖。时光已经进入了新的冰川期，地质学家们称之为更新世。大约在200万年前大量冰川开始向前移动，有时覆盖地球陆地表面的1/4，厚达数千英尺。在这最后一个冰冻时期，冰川由于至少有4次溶化，因此，出现了几度前进、几度后退的现象。现在人们开始发现一些证据表明，冰川在下一次推进时总比前一次更凶猛。最凶的一次大约发生在5万年前，到1万年前停止。每当出现间冰期，全世界的气候就平均变暖，比现在还要暧得多。通常间冰期要持续好几千年。即使在最后这次冰川推进的高峰期，也有过若干次停止前进、发生溶化的过程，全世界的气温也在慢慢回升，也有上下波动。科学家们认为地球仍然处在冰川阶段，因为1/10的地球表面仍然被坚冰覆盖。格陵兰和南极地面上覆盖着共达500万立方英里的冰，世界各地崇山峻岭中峡谷冰川更是司空见惯。但是历史记载清楚的表面，100年来地球正在经历一次间冰期。瑞士在本世纪初兴建的游览胜地曾使游客对冰雪美景一览无遗，而现在，那冰雪世界早已荡然无存！如果这次间冰期继续下去，地球上的冰川全部溶化，海面将上升200～300英尺，淹没全世界许多大城市。像纽约、波士顿只能由背负水下呼吸器的蛙人去参观游览了。也许这次间冰期是暂时的，在未来的数千年中地球将会再次变冷，再次经受冰冻。巨大的冰山将再次出现并向世界各地推进，吞没前进道路上的一切文明。或许冰川期确实正在结束：这一切只有让时间和被淹没的沿海城市能说清楚。

在漫长的地质史上，地球曾历经三次温度持续下降的时期，地理学家将之称为“冰河期”，其中前寒武纪与古生代的冰河期持续了几千万年，新生代的冰河期则持续了两百万年。 关于冰河期的成因学界至今仍无一定论，部份学者认为，可能和地球自转时，地轴周期性倾斜角度的改变，导致阳光照射量减少有关。冰河期的发生，至今仍是自然科学的一个谜。虽然科学家已相当肯定地球的绕日轨道和自转轴的变化，与冰河期的发生有密切的关系，但这些变化并不会改变太阳的入射能量，只改变了入射阳光的分布，却能引起地球上气候极大的变化，这令科学家十分困惑。 大约是人类刚出现在地球舞台的两百万年前，地质史上第三次冰河期“第四纪冰河期”同时揭开序幕，全球各地气温开始下降，北半球中纬度地区的欧洲、北美洲和格陵兰，都被北极一路延伸过来的大冰盖所复盖。这段期间，欧洲共发生了五次冰河期，北美洲及中国大陆则发生了四次冰河期。至于台湾，目前只确定雪山地区在最后一次冰河期，也就是七至一万年前的更新世晚期曾发生过冰河。学者们将其称之为“雪山冰期”。

Ice Age 可用于书面语，但更偏向语口头语。Glacier period 最多只能用在论文里！ 嘎嘎

冰河时期是地球气候沉於长期低迷、极地冰川幅盖大陆的一个时期，由冰川扩展现象导致。概要冰河时期时间可以维持超过一百万年，地球形成以来冰河时期曾出现过十一次，上一个冰河时期称为「大冰河时代」，发生於距今一万八千年前，结束於一万年前，当时地球约三分之一的陆地被覆盖在240米厚的冰层下。[来源请求]冰河时期期间，温度下降，改变了地球表面的植物相和生物的生存环境，许多生物因此面临灭亡或被迫迁移，只有能够适应环境的物种，才能幸存下来。[来源请求][编辑] 原因冰河时间发生原因，仍有待研究，科学家相信主要是因为地球跟太阳距离拉远了，令地球吸收自太阳的能量减少，所以令气温下降。[来源请求][编辑] 大冰期 5亿年来的纪录显示现今和最近的两次大冰期地球史上主要有四次的大冰期[来源请求]。其中8亿 ~ 6亿年前的成冰纪可能是地球史上最严峻的冰期，当时可能整个地球都被冰层所覆盖。而该冰期的结束可能间接促成了后来的寒武纪生命大爆发，但这个理论仍有争议。名称 年代 (年) 纪 代 3千万年前至今 第三纪 新生代 卡鲁冰期Karoo 3亿6千万年前至2亿6千万年前 石炭纪和二叠纪 古生代 安第-撒哈拉冰期Andean-Saharan 4亿5千万年前至4亿2千万年前 奥陶纪和志留纪 古生代 瓦兰吉尔冰期Cryogenian(or Sturtian-Varangian) 8亿年前至6亿3千5百万年前 成冰纪 元古宙 休伦冰期Huronian 24亿年前至21亿年前 成铁纪和层侵纪 元古宙 [编辑] 更新世冰期 65万年来南极洲的冰蕊所记录的大气二氧化碳浓度而划分的冰期/间冰期周期距离现代较近的更新世冰期的间冰期约为4万年[来源请求]，而后缩短为1万年。上一次冰河期是约1万年前[来源请求]。名称 间冰期/冰期 年代 (年) MIS 世 间冰期 1万2千年前 至 今 MIS1 全新世 沃姆冰期Würm 冰河期 11万年前 至 1万2千年前 MIS2-4& 5a-d 更新世 里斯-沃姆间冰期Riss-Würm 间冰期 13万年前 至 11万年前 MIS5e 里斯冰期Riss 冰河期 20万年前 至 13万年前 MIS6 民德-里斯间冰期Mindel-Riss 间冰期(s) 30/38万年前 至 20万年前 MIS7 民德冰期Mindel 冰河期(s) 45万5千年前 至 30/38万年前 古萨-民德间冰期Günz-Mindel 间冰期(s) 62万年前 至 45万5千年前 古萨冰期Günz 冰河期 68万年前 至 62万年前 Waalian 间冰期 54万年前 至 47万年前 多瑙第二冰期Donau II 冰河期 55万年前 至 54万年前 Tiglian 间冰期 58万5千年前 至 55万年前 多瑙第一冰期Donau I 冰河期 60万年前 至 58万5千年前 Pastonian interglacial 间冰期 80万年前 至 60万年前 MIS63 Pre-Pastonian glaciation 冰河期 130万年前 至 80万年前 Bramertonian Interglacial 间冰期 155万年前 至 130万年前

The Big Chillby Kirk A. MaaschDuring the past billion years, the Earth's climate has fluctuated between warm periods - sometimes even completely ice-free - and cold periods, when glaciers scoured the continents. The cold periods - or ice ages - are times when the entire Earth experiences notably colder climatic conditions. During an ice age, the polar regions are cold, there are large differences in temperature from the equator to the pole, and large, continental-size glaciers can cover enormous regions of the earth.Ever since the Pre-Cambrian (600 million years ago), ice ages have occurred at widely spaced intervals of geologic time - approximately 200 million years - lasting for millions, or even tens of millions of years. For the Cenozoic period, which began about 70 million years ago and continues today, evidence derived from marine sediments provide a detailed, and fairly continuous, record for climate change. This record indicates decreasing deep-water temperature, along with the build-up of continental ice sheets. Much of this deep-water cooling occurred in three major steps about 36, 15 and 3 million years ago - the most recent of which continues today. During the present ice age, glaciers have advanced and retreated over 20 times, often blanketing North America with ice. Our climate today is actually a warm interval between these many periods of glaciation. The most recent period of glaciation, which many people think of as the "Ice Age", was at its height approximately 20,000 years ago. Although the exact causes for ice ages, and the glacial cycles within them, have not been proven, they are most likely the result of a complicated dynamic interaction between such things as solar output, distance of the Earth from the sun, position and height of the continents, ocean circulation, and the composition of the atmosphere.Climatic Cooling from 60 million years ago to present dayBetween 52 and 57 million years ago, the Earth was relatively warm. Tropical conditions actually extended all the way into the mid-latitudes (around northern Spain or the central United States for example), polar regions experienced temperate climates, and the difference in temperature between the equator and pole was much smaller than it is today. Indeed it was so warm that trees grew in both the Arctic and Antarctic, and alligators lived in Ellesmere Island at 78 degrees North. But this warm period, called the Eocene, was followed by a long cooling trend. Between 52 and 36 million years ago, ice caps developed in East Antarctica, reaching down to sea level in some places. Close to Antarctica, the temperature of the water near the surface dropped to between 5 and 8 degrees Celsius. Between 36 and 20 million years ago the earth experienced the first of three major cooling steps. At this time a continental-scale temperate ice sheet emerged in East Antarctica. Meanwhile, in North America, the mean annual air temperature dropped by approximately 12 degrees Celsius. Between 20 and 16 million years ago, there was a brief respite from the big chill, but this was followed by a second major cooling period so intense that by 7 million years ago southeastern Greenland was completely covered with glaciers, and by 5-6 million years ago, the glaciers were creeping into Scandinavia and the northern Pacific region. The Earth was once more released from the grip of the big chill between 5 and 3 million years ago, when the sea was much warmer around North America and the Antarctic than it is today. Warm-weather plants grew in Northern Europe where today they cannot survive, and trees grew in Iceland, Greenland, and Canada as far north as 82 degrees North.We are still in the midst of the third major cooling period that began around 3 million years ago, and its effect can be seen around the world, perhaps even in the development of our own species. Around 2 and a half million years ago, tundra-like conditions took over north-central Europe. Soon thereafter, the once-humid environment of Central China was replaced by harsh continental steppe. And in sub-Saharan Africa, arid and open grasslands expanded, replacing more wooded, wetter environments. Many paleontologists believe that this environmental change is linked to the evolution of humankind. Possible Explanations for the Past 60 Million Years of CoolingClimate change on ultra-long time scales (tens of millions of years) are more than likely connected to plate tectonics. Plate motions lead to cycles of ocean basin growth and destruction, known as Wilson cycles, involving continental rifting, seafloor-spreading, subduction, and collision. Several explanations of the latest cooling trend that involve a climate-tectonic connection are summarized below.Geographic Distribution and Size of ContinentsThrough the course of a Wilson cycle continents collide and split apart, mountains are uplifted and eroded, and ocean basins open and close. The re-distribution and changing size and elevation of continental land masses may have caused climate change on long time scales. Computer climate models have shown that the climate is very sensitive to changing geography. It is unlikely, however, that these large variations in the Earth's geography were the primary cause of the latest long-term cooling trend as they fail to decrease temperatures on a global scale.Likewise, changing topography cannot, by itself, explain this cooling trend. Computer model experiments performed to test the climate's sensitivity to mountains and high plateaus show that plateau uplift in Tibet and western North America has a small effect on global temperature but cannot explain the magnitude of the cooling trend. Plateau uplift does, however, have a significant impact on climate, including the diversion of North Hemisphere westerly winds and intensification of monsoonal circulation.Geometry of Ocean BasinsAnother theory explaining these changes in climate involves the opening and closing of gateways for the flow of ocean currents. This theory suggests that the redistribution of heat on the planet by changing ocean circulation can isolate polar regions, cause the growth of ice sheets and sea ice, and increase temperature differences between the equator and the poles.Ocean modeling experiments suggest that the ocean could not have carried enough heat to the poles to maintain the early warm climates. But atmospheric climate modeling experiments show that even if the ocean did transport enough heat up to the coast of Antarctica to maintain sea surface temperatures at 10 to 15 degrees Celsius, the interior conditions would still be much colder - and this is contrary to the geologic record. It is possible, however, that changes in heat transport caused by variations in ocean gateways may have played a significant role in cooling trends over the last 60 million years, and, in particular, may help explain some of the relatively sudden cooling events. Atmospheric Carbon DioxideChanges in the concentration of carbon dioxide in the atmosphere are a strong candidate to explain the overall pattern of climatic change. Carbon dioxide influences the mean global temperature through the greenhouse effect. The globally averaged surface temperature for the Earth is approximately 15 degrees Celsius, and this is due largely to the greenhouse effect. Solar radiation entering earth's atmosphere is predominantly short wave, while heat radiated from the Earth's surface is long wave. Water vapor, carbon dioxide, methane, and other trace gases in the Earth's atmosphere absorb this long wave radiation. Because the Earth does not allow this long wave radiation to leave, the solar energy is trapped and the net effect is to warm the Earth. If not for the presence of an atmosphere, the surface temperature on earth would be well below the freezing point of water.Through a million year period, the average amount of carbon dioxide in the atmosphere is affected by four fluxes: flux of carbon due to (1) metamorphic degassing, (2) weathering of organic carbon, (3) weathering of silicates, (4) burial of organic carbon. Degassing reactions associated with volcanic activity and the combining of organic carbon with oxygen release carbon dioxide into the atmosphere. Conversely, the burial of organic matter removes carbon dioxide from the atmosphere.Plate collisions disrupt these carbon fluxes in a variety of ways, some tending to elevate and some tending to lower the atmospheric carbon dioxide level. It has been suggested that the Eocene, the early warm trend 55 million years ago, was caused by elevated atmospheric carbon dioxide and that a subsequent decrease in atmospheric carbon dioxide led to the cooling trend over the past 52 million years. One mechanism proposed as a cause of this decrease in carbon dioxide is that mountain uplift lead to enhanced weathering of silicate rocks, and thus removal of carbon dioxide from the atmosphere.In addition, the collision of India and Asia led to the uplift of the Tibetan Plateau and the Himalayas. While topography may not be enough to explain the cooling trends, another mechanism may account for changing climate. The uplift may have caused both an increase in the global rate of chemical erosion, as well as erode fresh minerals that are rapidly transported to lower elevations, which are warmer and moister and allow chemical weathering to happen more efficiently. Through these mechanisms, then, it has been hypothesized that the tectonically driven uplift of the Tibetan Plateau and the Himalayas is the prime cause of the post-Eocene cooling trend.Kirk A. Maasch is a professor at the University of Maine, in the Department of Geological Sciences.