本文提出了宜昌奥陶系沉积相是台地相—台地边缘相—浅海盆地相的多相台棚式的组合类型，指出奥陶系经历了四次海进到海退的沉积旋回过程。
In this paper, it is suggested that the Ordovician sedimentary facies in the Yichang region are a combination type consisting of platform facies, platform margin facies and shallow sea basin facies.
我们通过一架望远镜观察了停留在岩架上的一只海鹦：它在张望，思索，忽进忽退。
Through a telescope we watched the unfolding drama of a puffin on a ledge, peering over the edge, thinking better of it, retreating, advancing, retreating.
这些孢粉化石资料说明区域性植被响应气候演变、海进、海退等所发生的变化。
These fossil data indicate the changes in regional vegetation in response to climate variations and Marine transgressions and regressions.
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