广东快乐十分

口语提升

综合

手机APP下载

您现在的位置: 广东快乐十分 > 在线广播 > 科学美国人 > 科学美国人地球系列 > 正文

科学美国人60秒:不易察觉的远古足迹浮出水面

来源:可可英语 编辑:aimee    |  可可官方微信:ikekenet
sCC78^A=FphQ]*@Pj

JxxQ6TJyhwm5hR*8d6l3

This is Scientific American's 60-second Science, I'm Eliene Augenbraun.
Fossil footprints help tell us how ancient people lived. But such physical impressions are hard to find.
"You get all of these footprints from different species in the same time period interacting, and you can't see them all the time. And some of them, you can never see—with the eye, that is. But we can we can still detect them with geophysical sensors."
Cornell University archaeologist Thomas Urban. He and colleagues used ground-penetrating radar (GPR) to detect invisible traces of footsteps in White Sands National Monument in New Mexico. Their GPR device goes back and forth over an area in a grid pattern, which ultimately creates a 2-D radargram. The technique detects subtle differences in ground density.
Speaking about one set of otherwise imperceptible animal's footprints, he says:
"These were caused by compression of sediment beneath the animal's track. And they relate to广东快乐十分 the weight and momentum of the animal."

BORjqDyBYt1

远古足迹.jpg
Twelve thousand years ago, the White Sands area was a large, muddy flat, which was covered with footprints from various species. Urban is excited about the stories so many footsteps suggest. For example, the researchers found no evidence of shoes or sandals. They did find human and animal tracks crossing each other—which suggests the prints were left during a hunt.
The findings are reported in the journal Scientific Reports.
"This sort of unique setting has recorded all of the daily movements of people. They are actually more than we even thought because there are always some that aren't visible."
These techniques could be applied to older sites all around the world, perhaps even to find dinosaur tracks that have been sitting quietly—waiting, at long last, to be found.
Thanks for listening for Scientific American's 60-second Science. I'm Eliene Augenbraun.

~RhzgPRN]V%

J]WOdYXOtu(T(mbM

*%v#)Ghe(4gMI!V&ebkbYw@=&.KDMCex2XpL7LcJdOYLPC[t%t^

重点单词   查看全部解释    
['spi:ʃiz]

想一想再看

n. (单复同)物种,种类

 

想一想再看

n. 轨道(track的复数);磁道;轮胎

 
[in'vizəbl]

想一想再看

adj. 看不见的,无形的
n. 隐形人(或物

 
['ʌltimitli]

想一想再看

adv. 最后,最终

 
[ju:'ni:k]

想一想再看

广东快乐十分adj. 独一无二的,独特的,稀罕的

联想记忆
['setiŋ]

想一想再看

n. 安装,放置,周围,环境,(为诗等谱写的)乐曲

 
[.impə'septəbl]

想一想再看

广东快乐十分adj. 感觉不到的,细微的

联想记忆
['densiti]

想一想再看

广东快乐十分n. 密集,密度,透明度

 
['ə:bən]

想一想再看

广东快乐十分adj. 城市的,都市的

联想记忆
[tek'ni:k]

想一想再看

n. 技术,技巧,技能

 


关键字:

发布评论我来说2句

    特别推荐

      ·
      ·
      ·
      ·

    最新文章

    可可英语官方微信(微信号:ikekenet)

    每天向大家推送短小精悍的英语学习资料.

    添加方式1.扫描上方可可官方微信二维码。
    添加方式2.搜索微信号ikekenet添加即可。