< blockquote > < p >标准地层命名法是基于古生物的年代地层系统的间隔时间由认可的化石组合。< / p > < /引用> < p >这是维基百科。这是不正确的。全球界线层型剖面点的点(委员会)是识别一个全球性的边界与一个非常具体的典型的例子。尽管辨认和全球化石组合优先,有时有更好的选择,有时这样的组合不存在。例如,< / p > < p >地层边界,标志着开始的新生代,(和下第三系古新世系列和丹麦阶阶段)是一个< a href = " http://www.stratigraphy.org/GSSP/Danian.html " rel = " nofollow noreferrer " >毫米厚层环保粘土铺平道路附近的> < / El迷离恍惚,突尼斯。这于大约6600万年前铺设粘土层,可以发现在世界上许多地方。这一层是截然不同的,独特的,全球发生。粘土层包含恐龙杀手小行星的残余。< / p > < blockquote > < p >在显生宙地层界限定义如何?< / p > < /引用> < p >去点的问题,在< a href = " http://www.stratigraphy.org/GSSP/Ediacaran.html " rel = " nofollow noreferrer " >的埃迪卡拉< / >”被定义为的基础Marinoan帽碳酸(Nuccaleena形成)Enorama溪的弗林德斯山脉中部,阿德莱德裂谷复杂,南澳大利亚。” The GSSP is the archetype, but as with that thin layer of red clay, this layer of cap carbonate can be found in many places around the world. That layer of cap carbonate represents when a worldwide glaciation event ended. All of the International Commission on Stratigraphy boundaries that predate the base of the Ediacaran are currently defined in terms of time called Global Standard Stratigraphic Ages (GSSAs). That's a fancy name for a rather arbitrary point in time.