It behaves more or less like a solid, but over long periods of time, geologic periods of time, it can flow.

它的行为或多或少有点像固体，但在很长的时间周期里（地质学意义上的周期），它其实是流动的。

They can reveal what species lived during certain geologic periods, how they lived, and how they interacted with their environment.

它们可以揭示特定地质时期生活的物种、它们的生活方式以及它们如何与环境相互作用。

In his hand he wielded with ease an enormous bough, a staff worthy of this shepherd of the geologic period.

他手中轻松地挥舞着一根巨大的树枝，这根手杖配得上这位地质时期的牧羊人。

So sediment is transported and then deposited and it forms layers on the Earth ’ s surface over time. We examine these layers to learn about different geologic time periods including when they began and ended.

因此沉积物被运输然后沉积下来，随着时间的推移在地球表面形成层。我们检查这些层以了解不同的地质时期，包括它们开始和结束的时间。