词条 | Cenomanian Stage |
释义 | Cenomanian Stage geology first of six main divisions (in ascending order) in the Upper Cretaceous Series, representing rocks deposited worldwide during the Cenomanian Age, which occurred 99.6 to 93.5 million years ago during the Cretaceous Period. Rocks of the Cenomanian Stage overlie those of the Albian Stage and underlie rocks of the Turonian Stage. The name for this stage is derived from Cenomanum, the Roman name for Le Mans in northwestern France. The Cenomanian has been divided into several biozones (biozone) representing shorter spans of time and characterized by fossil ammonite (ammonoid) genera that are used as index fossils (index fossil). |
随便看 |
百科全书收录100133条中英文百科知识,基本涵盖了大多数领域的百科知识,是一部内容开放、自由的电子版百科全书。