GEOLOGICAL TIME

Question 1

o Absolute age dating

Answer 1

(radiometric dating)
 Decay products of radioactive elements in minerals to get absolute ages
* Igneous rocks, metamorphic rocks

Question 2

o Relative age dating

Answer 2

(this is older than that)
 Steno’s principles

Question 3

principle behind half-life

Answer 3

– isotopes are variants of the same parent atom, differing in #of neutrons,

Question 4

o Formula- measured by ratio of parent to daughter

Answer 4

 N(t) = N0(1/2) ^t/t1/2

Question 5

half-life

Answer 5

the time required for half of the radioactive nuclei in a sample to decay

Question 6

o Nonconformity

Answer 6

 A boundary between non-sedimentary rocks (below) and sedimentary rocks (above)
* Occurs when time passes before deposition og the next layer
* Layer is eroded.

Question 7

disconformity

Answer 7

 A boundary between two sequences of sedimentary rocks where the underlying nest have been eroded (no tilted) prior to the deposition of the younger ones

Question 8

o Angular unconformity

Answer 8

 A boundary between two sequences of sedimentary rocks where the underlying ones have been tilted or folded and eroded prior to the deposition of the younger ones

Question 9

o Para conformity

Answer 9

 A time gap in a sequence of sedimentary rocks that does not show up as an angular unconformity or a disconformity

Question 10

different types of unconformities

Answer 10

nonconformity
disconformity
angular unconformity
para conformity

Question 11

o What determines a time boundary (4)

Answer 11

 Appearance of new species
 Extinction events
 Shifts in ciliate
 Natural catastrophes

Question 12

o Hadean eon (4.54-4.0 Ga)

Answer 12

 No evidence of life
 Differentiation of earths layers
 Development of atmosphere and oceans

Question 13

o Archean eon (4.0-2.5 Ga)

Answer 13

 Oldest known fossils
 Free oxygen not available
 First continents form

Question 14

o Proterozoic eon (2.5Ga- 451 Ma)

Answer 14

 Great oxygenation event
 Protocontinents accrete and form supercontinents
 Snowball earth ~700Ma
 First microscopic and macroscopic multicellular life ~550 Ma
 First eukaryotes
 Cambrain explosion

Question 15

o Phanerozoic eon (541 Ma- present)

Answer 15

 Marked by the Cambrain explosion and the diversity of life forms
 Paleozoic, Mesozoic, and Cenozoic mean old, middle and new life

Question 16

• Order the 3 eras that make up our current eon

Answer 16

o Paleozoic, Mesozoic, cenozoic

Question 17

eons

Answer 17

haden, archean, proterzoic, phanerozoic

Question 18

mass extinctions

Answer 18

o End-ordovician
o End-devonian
o End-permian
o End-triassic
o End-cretaceous

Question 19

o End-ordovician

Answer 19

rapid melting of glacier

Question 20

o End-devonian

Answer 20

rapid climate change, O2 levels change and volcanic activity

Question 21

end- permian

Answer 21

extreme volcanic activity (siberian LIP)

Question 22

end triassic

Answer 22

splitting of pangea - CO2 volume

Question 23

end cretaceous

Answer 23

meterite impact