After two half-lives, there is no longer any of the original radioactive material remaining. a) true
b) false

When studying the calumet region of illinois and indiana alfred meyers noted four stages of development as new groups occupied this land in stage 2 farmers used the land primarily to grow food for their familes and their small communities

Can someone me with this plz? ! i'm putting 20 points on it!

Which is a trait of a index fossil ?