第2006期:Antarctica Was Once Home to Rivers, Forests

Antarctica has not always been a land of ice and snow. Earth's southernmost continent once was home to rivers and forests full of life. 

南极洲并不总是冰天雪地。 地球最南端的大陆曾经是充满生机的河流和森林的家园。 

Scientists are using satellite observations and radar imagery to look deep under the ice. The researchers report finding a large ancient landscape buried under the continent's ice sheet. It is full of valleys and ridges, shaped by rivers before being covered by glaciers long ago. 

科学家们正在利用卫星观测和雷达图像来观察冰层深处。 研究人员报告称，在该大陆的冰盖下发现了巨大的古代景观。 它充满了山谷和山脊，在很久以前被冰川覆盖之前由河流塑造而成。 

The landscape is located in East Antarctica's Wilkes Land area bordering the Indian Ocean. It covers an area about the size of Belgium. The researchers said the landscape appears to date to at least 14 million years ago and perhaps beyond 34 million years ago, when Antarctica entered its deep freeze. 

该景观位于东南极洲毗邻印度洋的威尔克斯地地区。 它的面积大约相当于比利时的面积。 研究人员表示，这片地貌似乎可以追溯到至少 1400 万年前，甚至可能超过 3400 万年前，当时南极洲进入深度冰冻状态。 

"The landscape is like a snapshot of the past," said Stewart Jamieson. He is a professor of glaciology at Durham University in England and co-leader of the study published in the journal Nature Communications. 

“这里的风景就像是过去的快照，”斯图尔特·贾米森说。 他是英国杜伦大学冰川学教授，也是发表在《自然通讯》杂志上的这项研究的共同领导者。

"It is difficult to know what this lost world might have looked like before the ice came along, but it was certainly warmer back then,” Jamieson added. “Depending how far back in time you go, you might have had climates that ranged anywhere from the climate of present-day Patagonia through to something more approaching tropical.” 

贾米森补充道：“很难知道这个失落的世界在冰层出现之前会是什么样子，但当时肯定更温暖。”“取决于你回溯到多久以前，你可能经历过任何地方的气候变化 从现在的巴塔哥尼亚气候到更接近热带的气候。” 

Such an environment likely would have been populated by wildlife, Jamieson said. But the area’s fossil record is too incomplete to know which animals may have lived there. 贾米森说，这样的环境很可能是野生动物的栖息地。 但该地区的化石记录太不完整，无法确定哪些动物可能生活在那里。

The ice above the ancient landscape measures about 2.2 kilometers to 3 kilometers thick, said study co-leader Neil Ross. He is a professor of polar science and environmental geophysics at Newcastle University in England. 

研究共同负责人尼尔·罗斯 (Neil Ross) 表示，古代景观上方的冰厚约 2.2 公里至 3 公里。 他是英国纽卡斯尔大学极地科学和环境地球物理学教授。

The researchers said the surface of the planet Mars is better known than the earth surface below the ice in Antarctica. They said one way to learn more would be to drill through the ice and take a piece of the earth below. This could uncover evidence showing ancient life, as was done with samples taken in Greenland dating back two million years ago. 

研究人员表示，火星表面比南极洲冰层以下的地球表面更为人们所知。 他们说，了解更多信息的一种方法是钻穿冰层并获取下面的一块地球。 这可能会发现显示古代生命的证据，就像在格陵兰岛采集的样本可以追溯到两百万年前一样。 

Some earlier studies have uncovered ancient landscapes beneath Antarctica's ice including mountains. But the landscape discovered in the new study was the first of its kind. 

一些早期的研究发现了南极洲冰层下的古代景观，包括山脉。 但这项新研究中发现的景观是同类中的第一个。 

Right before 34 million years ago, Antarctica's landscape and wildlife was likely similar to today's cold temperate rainforests. That includes places like Tasmania, New Zealand and South America's Patagonia area, Ross added. 

就在 3400 万年前，南极洲的地貌和野生动物可能与今天的冷温带雨林相似。 罗斯补充说，这包括塔斯马尼亚、新西兰和南美洲的巴塔哥尼亚地区等地。 

Antarctica was once part of the Gondwana supercontinent that also included what is now Africa, South America, Australia, the Indian subcontinent and the Arabian Peninsula. But it eventually split off in a process called plate tectonics. 

南极洲曾经是冈瓦纳超大陆的一部分，该超大陆还包括现在的非洲、南美洲、澳大利亚、印度次大陆和阿拉伯半岛。 但它最终在一个称为板块构造的过程中分裂。 

Jamieson said the researchers think that when Antarctica's climate was warmer, rivers flowed toward a continental coastline that was created as the other land masses broke away. When the climate cooled, he said, some small glaciers formed on hills next to the rivers, with valleys deepening as glaciers eroded. 

贾米森说，研究人员认为，当南极洲的气候变暖时，河流流向大陆海岸线，而大陆海岸线是随着其他陆地的分离而形成的。 他说，当气候变冷时，河流旁边的山上就会形成一些小冰川，而山谷也会随着冰川的侵蚀而加深。 

When the climate cooled even more, an ice sheet grew which covered the whole continent, Jamieson added. Eventually, “the landscape got preserved, likely for 34 million years.” 

贾米森补充说，当气候进一步变冷时，冰盖就会生长并覆盖整个大陆。 最终，“这片景观得到了保存，很可能保存了 3400 万年。”