Also known as Eratosthenian period
The Eratosthenian period in the lunar geologic timescale runs from 3.2 billion years ago to 1.1 billion years ago. It is named after the crater Eratosthenes, which displays characteristics typical of craters of this age, including a surface that is not significantly eroded by subsequent impacts, but which also does not possess a ray system. The massive basaltic volcanism of the Imbrian period tapered off and ceased during this long span of lunar time. The youngest lunar lava flows identified from orbital images are tentatively placed near the end of this period.
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爱拉托逊纪（Eratosthenian period）是月球地质年代中从32亿年前至11亿年前间的一段时期，处于晚雨海世和哥白尼纪之间。它的名称取自该时期典型的撞击坑-厄拉多塞陨石坑。跨度范围，特别是上限尤为清晰明确，开始于31.1-32.4亿年前，而终结期最普遍的看法是介于11-22亿年前之间，其标志则是哥白尼环形山的出现。 爱拉托逊纪期限的界定： * 起点：月球主要地貌为月海地形，所有大于确定尺寸的陨石坑，尚未被撞击的陨石轰平，即：这些区域中直径大于240±10米的陨石坑，其内侧壁坡倾斜率为1°。 * 终点：通常所认为的古老陨石坑仍保留有射纹系统，但事实上该界限尚无明确的定义。它的定义很复杂，因为，不仅有已发现的陨石坑年龄问题，而且不同情况下射纹线的消失速率也不同。（另请参阅哥白尼纪）。 爱拉托逊纪是1962年由月球现代地质史划分创始人尤金·舒梅克和罗伯特·哈克曼（Robert Hackman）所提出。
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Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).