Geologic Time Scale

Question 1

determine whether a rock is younger or older than other rocks

Answer 1

relative dating

Question 2

uses radiometric dating techniques to determine how long ago a rock formed in the exact number of years

Answer 2

absolute dating

Question 3

accounts for 88% of the earth’s history; earth had a hot, steaming, hostile landscape

Answer 3

precambrian period

Question 4

little is known because few rocks existed; condition is like hell

Answer 4

hadean

Question 5

crustal building and formation of volcanic belts and sedimentary basins due to plate tectonics

Answer 5

archaean

Question 6

rifting of continental crust and subsequent filling with sedimentary and volcanic rocks

Answer 6

proterozoic

Question 7

earth forms, first prokaryotic cells in stromatolites appear, first eukaryotic cells appear, multicellular organisms appear

Answer 7

precambrian period

Question 8

marked by the beginning of life

Answer 8

paleozoic era

Question 9

invertebrates dominate and marine algae prosper

Answer 9

cambrian

Question 10

invertebrates diversify and jawless fishes appear

Answer 10

ordovician

Question 11

seedless vascular plants and first jawed fishes appear

Answer 11

silurian

Question 12

first seed plants appear and jawed fishes diversify

Answer 12

devonian

Question 13

known as age of fishes

Answer 13

devonian

Question 14

amphibians diversify and first reptiles appear

Answer 14

carboniferous

Question 15

reptiles diversify and conifers appear

Answer 15

permian

Question 16

pangea rifted into ___________ and ___________

Answer 16

northern laurasia and southern gondwanaland

Question 17

during this time, pangaea rifted into 2

Answer 17

mild mesozoic

Question 18

new trees such as conifers appeared and mammals were just beginning to emerge

Answer 18

mesozoic era

Question 19

first mammals and dinosaurs appear; corals and mollusks dominate seas

Answer 19

triassic

Question 20

dinosaurs prosper and birds appear

Answer 20

jurassic

Question 21

placental mammals and modern insects appear

Answer 21

cretaceous

Question 22

known as age of mammals or age of recent life

Answer 22

cenozoic era

Question 23

last 66 mil years of earth’s history

Answer 23

cenozoic era