简介:DefinitionofanewgeologicperiodfortheIastintervaloftheProterozoicEon,theEdiacaran,wasrecentlyratifiedbytheIUGS.TheEdiacaranPeriodisthefirstProterozoicperiodtoberecognizedonthebasisofchronostratigraphiccriteria,thefirstinternationallyratified,chronostratigraphicallydefinedperiodofanyagetobeintroducedinmorethan120years,andthefirsttobedefinedbya“goldenspike”intheSouthernhemisphere.