Why Isn't the Precambrian More Finely Divided into Sub-Divisions Like

Multiple Choice

Why isn't the Precambrian more finely divided into sub-divisions like periods and epochs?

A) Fewer and less diverse fossils exist in Precambrian rocks.
B) Precambrian rocks don't have radioactive isotopes in them.
C) Geologists just don't care about the Precambrian the way they do about more recent time periods.
D) The Precambrian lacks the igneous rocks that are most useful for radiometric dating.