- 1前寒武紀
Precambrian names the huge stretch of Earth’s story that comes before the Cambrian time. In older it runs from about 4,600 million years ago — when a hard outer skin of rock first formed on the Earth — to about 570 million years ago. Though actually, scientists now put the start of the Cambrian nearer 541 million years ago, and they no longer treat “the Precambrian” as one neat period. It is a handy label for almost 90 percent of Earth’s life: the Hadean, Archean, and Proterozoic eons sitting under one umbrella. The tidy line “that is when simple life first appeared” is tidier than the rocks. Simple life, the kind too small to see, was already here for a very long time; what changes around the Cambrian is that many kinds of animals with hard parts show up clearly in fossils. You use Precambrian as an adjective (Precambrian rock, Precambrian time) and as a name for that whole span (the Precambrian). In careful writing it takes a capital P, because it is a proper name in geology, not a common describing word.
組成From pre- “before” + Cambrian. Cambrian is the next named time in the rock record, itself named from Cambria, the old Latin name for Wales, where those rocks were first closely studied.
同家族的字
- Cambrianthe period that follows; Precambrian is everything before it
原始詞典資料2 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
Precambrianadj/priːˈkam.bɹɪ.ən/
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informalgeographygeologynatural-sciencesRelating to the time and geology dated before the Phanerozoic
- When you look at a Precambrian trilobite in the lobby of a New York bank, it is difficult to speculate about its primeval environment.
Precambrianname/priːˈkam.bɹɪ.ən/
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geographygeologynatural-sciencesThe Precambrian supereon; spanning from the formation of the Earth around 4.6 billion years ago to the emergence of hard-shelled creatures 541 million years ago.
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。