ChaseDream
搜索
返回列表 发新帖
00:00:00

Charcoal from a hearth site in Colorado, 2,000 miles south of Alaska, is known to be 11,200 years old. Researchers reasoned that, since glaciers prevented human migration south from the Alaska-Siberia land bridge between 18,000 and 11,000 years ago, humans must have come to the Americas more than 18,000 years ago.

Which of the following pieces of new evidence would cast doubt on the conclusion drawn above?

正确答案: D

更多相关帖子

524

帖子

15

好友

4712

积分

ChaseDream

注册时间
2003-03-17
精华
8
解析
查看: 2411|回复: 1
打印 上一主题 下一主题

gwd 41逻辑 谢谢

[复制链接]
跳转到指定楼层
楼主
发表于 2010-9-21 12:29:30 | 只看该作者 回帖奖励 |正序浏览 |阅读模式
charcoal from a hearth site in Colorado, 2000miles south of Alaska, is known to be 11200 years old. Researchers reasoned that, since glaciers prevented human migration south from the Alaska-Siberia land bridge between 18000 and 11000 years old, humans must have come to the Americas more than 18000 years ago.
which of the following pieces of new evidence would cast doubt on the conclusion drawn above?

A using new radiocarbon dating techniques, it was determined that the charcoal from the Colarado site was at least 11400 years old.

B another campsite was found in New Mexico with remains dated at 16000 years old.

C a computer simulation of glacial activity showed that it would already have been impossible for humans to travel south overland from Alaska 18500 years ago.

D using new radiocarbon dating techniques, it was proved that an ice-free corridor allowed passage south from the Alaska-Siberia land bridge at least 11400 years ago.

E studies of various other hunting-gathering populations showed convincingly that, once the glaciers allowed passage, humans could have migrated from Alaska to Colarado in about 20 years.

不太明白题目什么意思,,答案选D
收藏收藏 收藏收藏
沙发
发表于 2010-9-21 14:25:15 | 只看该作者
原文说since glaciers prevented human migration south from the Alaska-Siberia land bridge between 18000 and 11000 years old,说明它认为人不可能在这段时间从c到a

D说有个有个corridor是可以让他们穿越的,因此削弱了结论。
您需要登录后才可以回帖 登录 | 立即注册

手机版|ChaseDream|GMT+8, 2024-11-14 13:31
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号

ChaseDream 论坛

© 2003-2023 ChaseDream.com. All Rights Reserved.

返回顶部