Geologic Time Scale Table

Question 1

how many eons

Answer 1

4

Question 2

how many eras

Answer 2

3

Question 3

Earth’s formation; formation of the moon; heavy bombardment

Answer 3

hadean eon

Question 4

First single-celled
organisms; first continents form

Answer 4

archean eon

Question 5

First eukaryotes; Great Oxygenation Event

Answer 5

proterozoic, paleoproterozoic

Question 6

First multicellular organisms

Answer 6

proterozoic, mesoproterozoic

Question 7

First animals; snowball Earth glaciations

Answer 7

proterozoic, neoproterozoic

Question 8

First trilobites,
brachiopods, and echinoderms

Answer 8

phanerozoic, paleozoic, cambrian, furongian

Question 9

First vertebrates;
Ordovician-Silurian extinction event

Answer 9

phanerozoic, paleozoic, ordovician, hernantian

Question 10

First vascular plants;
Silurian-Devonian extinction event

Answer 10

phanerozoic, paleozoic, silurian, pridoli

Question 11

First fish; first tetrapods

Answer 11

phanerozoic, paleozoic, devonian, frasnian

Question 12

First insects; first reptiles

Answer 12

phanerozoic, paleozoic, carboniferous, pennsylvanian

Question 13

first coal forrest

Answer 13

phanerozoic, paleozoic, carboniferous, mississippian

Question 14

Permian-Triassic extinction event, largest mass extinction in Earth’s history

Answer 14

phanerozoic, paleozoic, permian, lopingian

Question 15

rise of dinosaurs

Answer 15

phanerozoic, mesozoic, triassic, rhaetian

Question 16

giant dinasaurs, first birds

Answer 16

phanerozoic, mesozoic, jurassic, tithonian

Question 17

Cretaceous-Paleogene extinction event, killing off non-avian dinosaurs and leading
to the rise of mammals

Answer 17

phanerozoic,mesozoic, cretaceous, maastritchtian

Question 18

early mammals first primates

Answer 18

phanerozoic, cenozoic, paleogene, eocene

Question 19

Recovery from
Cretaceous-Paleogene extinction event

Answer 19

phanerozoic, cenozoic, paleogene, paleocene

Question 20

Ice Age begins; first hominins

Answer 20

phanerozoic, cenozoic, neogene, miocene

Question 21

Ice Age reaches its peak; humans evolve

Answer 21

phanerozoic, cenozoic, quaternary, pliestocene

Question 22

Current period; rise of human civilization

Answer 22

phanerozoic, cenozoic, quaternary, halocene