Earth Space Science Chapter 21 Sec. 2,3,4

Front 1

Radiometric dating

Back 1

determine ratio of parent
nuclei to daughter nuclei
(in a fossil or a rock).

Front 2

Half-life

Back 2

time it takes 1/2 of original
amount to decay.

Front 3

Dendrochronolgy

Back 3

science of comparing
annual growth rings in trees
to date events & change in
past environments.

Front 4

Varves

Back 4

accumulate in water, made
of sediments.

Front 5

Keybed

Back 5

distinctive layer that acts as
a time marker.

Front 6

Unconformity

Back 6

gap in rock layers--due to
erosion.

Front 7

Angular unconformity

Back 7

layers deposited; later
tilted/folded; new horizontal
layers deposited.

Front 8

Correlate

Back 8

match up layers of rock over
gr8 distances.

Front 9

Principle of
Uniformitarianism

Back 9

~the present is key to the past
~processes occuring today
have been occuring since the
earth formed

Front 10

Relative Age Dating

Back 10

place ages of rocks & events
that formed them in order but
w/out exact dates.

Front 11

Principles:

Back 11

1. Original Horizontality
2. Superposition
3. Cross-Cutting
4. Unconformity

Front 12

Original Horizontality

Back 12

sedimentary rocks are
deposited in horizontal layers.

Front 13

Superposition

Back 13

in an undisturbed rock
sequence, oldest are on
bottom, & ea. successive
layer is younger than layer
beneath.

Front 14

Cross-Cutting

Back 14

an igneous intrusion or a fault
is younger than the rock it
cuts across.

Front 15

Fossils

Back 15

evidence/remains of once
living plants or animals.

Front 16

Formation of Fossils:

Back 16

~quick burial
~presence of hard prts.

Front 17

Original Preservation

Back 17

frozen; tar pits; insects
trapped in amber.

Front 18

Perminerialization

Back 18

organic matter removed;
replaced w/ minerals;
petrified wood, bone.

Front 19

Molds

Back 19

cavity left in a rock when
organism's prts in a rock are
weathered & eroded.

Front 20

Cast

Back 20

produced when a mold is
filled w/ sediments &
hardens into a rock.

Front 21

Trace Fossils

Back 21

hand/foot prints
(not body parts)

Front 22

Evolution

Back 22

1 piece of support of fossils.

Front 23

Epochs

Back 23

smallest; m.y. to 10's m.y.

Front 24

Eon

Back 24

largest; longest unit by
(Phanerozoic)

Front 25

Era

Back 25

100's of m.y. to b.y.

(m.y. : millions of yrs.)
(b.y. : billions of yrs.)

Front 26

Period

Back 26

10's m.y. to 100's m.y.
(life forms found in fossil
record)

Front 27

Erosion

Back 27

A common cause of gaps in
rock layers.

Front 28

Fossils

Back 28

evidence/remains of once living plants or animals.

Front 29

Formation of Fossils:

Back 29

~quick burial
~presence of hard prts

Front 30

original preservation

Back 30

frozen; tar pits; insects trapped
in amber

Front 31

Permineralization

Back 31

organic matter removed;
replaced w/ minerals;
petrified wood, bone.

Front 32

Molds

Back 32

cavity left in a rock when
organism's prts in a rock are
weathered & eroded.

Front 33

Cast

Back 33

produced when a mold is filled w/ sediments & hardens into a rock.

Front 34

Trace Fossils

Back 34

hand/foot prints---
(not body parts).

Front 35

Evolution

Back 35

change; 1 piece of support
of fossils.

Front 36

Epochs

Back 36

smallest; m.y. to 10's m.y.

Front 37

Eon

Back 37

largest; longest unit b.y.
(Phanerozoic)

Front 38

Era

Back 38

100's m.y. to b.y.

Front 39

Period

Back 39

10's m.y. to 100's m.y.; life forms found in fossil record.