The stratigraphic contact shows that the Baidafan Formation is volcanic rocks of Early Cretaceous age.
地层接触关系表明白大畈组为早白垩世火山岩。
The best known and most widespread chalks are of Cretaceous age, such as those exposed in cliffs on both sides of the English Channel.
最有名最分布广泛的是白垩纪的白垩，如英吉利海峡两岸峭壁上暴露者。
The temporal analysis shows that Chinese gold placers were formed in the Quaternary whereas lode gold reserves are mainly of Jurassic-Cretaceous age, forming 64.
中国砂金矿主要形成在第四纪，而原生金矿则主要形成在侏罗—白垩纪（占原生金总储量64。
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