Question

how are eras and periods of the geologic time scale named?
o they are named for the places where geologists first described rocks or fossils from that time.
o their names are based on the names of scientists who discovered the rocks and fossils.
o they are named after plants and animals that lived during that time.
o their names are based on the number of centuries within that length of time.

Explanation:

Eras and periods of the geologic time scale are typically named for the places where geologists first described rocks or fossils from that time - period. This is a common practice in geology to identify and categorize different time - intervals based on the location of initial discoveries.

Answer:

They are named for the places where geologists first described rocks or fossils from that time.