This report summarizes the discovery of ca. 200 linear mounds along 40 km of the Des Moines River in central Iowa. Many of these mounds were mapped and recorded piecemeal over a century, but their ...

中文翻译：

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得梅因河谷中部的线性土丘集中区

本报告总结了大约的发现。爱荷华州中部得梅因河沿岸 40 公里长的 200 个线性土丘。许多土丘在一个多世纪的时间里被零碎地绘制和记录，但它们的......