amerikestrel wrote:In a book I got out of my school library, it says that the largest unit of time on the geologic time scale is the era. That contradicts what the wiki, wikipedia, and several others sites say. What is the correct answer to that?
I believe it is the eon, not the era.
Also, the same book says that the Precambrian is either a era or a period (I can't remember which), but according to wikipedia it's a supereon.

I checked the internet, and the general consensus seems to be that it is just called "Precambrian time" and is divided into the Hadean, Archean, and Proterozoic eons. But sometimes, it
is called the Precambrian eon.