An unusually high level of iridium appears at this time in the geologic record and is typically the biggest piece of evidence used in support of this theory.
An unusually high level of iridium appears at this time in the geologic record and is typically the biggest piece of evidence used in support of this theory.
在这一时期的地质记录当中，铱的高含量是用来证明这一理论的最有力的证据之一。