Geologic time 11-1

Which of the following is the correct order of time units from longest to shortest

• era, eon, epoch, period

• eon, era, period, epoch

• period, epoch, era, eon

• eon, epoch, era, period

Fossils in older rocks are smaller and less complex than fossils in younger rocks.

• true

• false

What did geologists use to mark divisions in geologic time

• absolute age of rocks

• slow change between species

• sudden changes in the fossil record

• relative age of rocks

How many mass extinctions have there been in Earth's history

• 2

• 9

• 17

• 5

What time period takes up about 90% of Earth's history

• Precambrian

• Cambrian

• Jurassic

• Triassic

How old are the oldest fossils in the fossil record

• 3 thousand years

• 3.5 billion years

• 7 billion years

• 600 million years

When did multicellular complex organisms start to show up in geologic time

• Precambrian

• Cambrian

• Cretaceous

• Holocene

the longest units of geologic time

• eon

• era

• period

• epoch

eons are subdivided into smaller units of time called

• periods

• eras

• epochs

• short eons

eras are subdivided into

• eons

• eras

• periods

• epochs