N-COUNT
(地质中的)世,纪,期
An epoch is a very long period of time in the earth's development, marked by particular physical or biological characteristics.
例句
Two main glacial epochs affected both areas during the last 100 million years of Precambrian times.
在前寒武纪的最后1亿年中,两个主要的冰川时期对两个地区都产生了影响。