首先，历史上的两次最大的撞击发生时间相距不到30万年——这是一个地质盲区。
First, two of the biggest impacts in history happened within 300, 000 years of each other—a geological eyeblink.
在地质历史上，适于前陆盆地发育的地球动力学环境，在时间和空间上均是相当有限的。
The geodynamic environment in which foreland basin is developed is rather limited both temporally and spatially in the geological history.
从这里可以了解地质时标的历史，地质时标的组成，也可以利用加州大学古生物博物馆的“时间机器”进入特定的地质时期。
It is also possible to read about the history of the geological time scale, and find out more about how it is organised, or go to a specific time period using the UCMP geologic time Machine.
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