Earth Science Unit 10

Front 1

absolute time

Back 1

enable scientist to determine the actual age of a rock, fossil or other object

Front 2

Genozoic

Back 2

most recent era

Front 3

correlation

Back 3

matching of rock outcrops of one geographic region to another

Front 4

era

Back 4

second longest time unit in the geological time scale, measured in hundreds of millions of years, and defined by differences in life forms that are preserved in rocks

Front 5

epoch

Back 5

time unit in th geological time scale, smaller than a period, measured in millions of years to tens of millions of years

Front 6

evolution

Back 6

adaptations of life forms to changing environmental conditions.

Front 7

fossil

Back 7

remains or evidence of a once living plant or animal

Front 8

fossil fuels

Back 8

nonrenewable energy resource fromed over geologic time from the compression and partial decomposition of organisms that lived millions of years ago.

Front 9

geologic timetable

Back 9

record of Earth's history from its origin to the present used to correlate geologic events, environmental changes and development of life forms that are preseved in rocks

Front 10

half life

Back 10

period of time it takes for a radioactive isotope such as carbon 14 to decay to one half of its original amount

Front 11

index or guide fossil

Back 11

remains of plants or animals that were abundant, widely distributed, and existed briefly that can be used by geologist to correlate or date rock layers

Front 12

key bed

Back 12

sediment layer that serves as a time marker in the rock record and rsults from volcanic ash or meteorite impact debris that spread out and covered large areas of Earth.

Front 13

Mesozoic

Back 13

middle era

Front 14

nonrenewable resources

Back 14

resource that exists in Earth's crust in a fixed amount and can be replaced only by geological, physical, or chemical processes tha can take hundreds of millions of years.

Front 15

Paleozoic

Back 15

oldest era

Front 16

period

Back 16

third longest time unit in the geological time scale, measured in tens of millions of years to hundreds of millions of years

Front 17

Proterozoic

Back 17

eon in the Precambrian Time

Front 18

radioactive decay

Back 18

Emission of atomic particles at a constant rate from a radioactive subsance and its resulting change into other elements over time

Front 19

relative time

Back 19

Placing rocks and the events that formed them in order by comparing them to other rocks and events. Without exact dates

Front 20

renewable resources

Back 20

Natural resources such as fresh air and most groundwater, that can be used indefinitely without causing a reduction the availbel supply

Front 21

Uncomformity

Back 21

gap in the rock record caused by erosion or weathering

Front 22

uniformitarianism

Back 22

states that processes such as mountain building, erosion, and sea level changes that are occurring today have been occurring since Earth formed

Front 23

hominid

Back 23

group of upright, bipedal primates inlcuding Homo sapiens

Front 24

ammonite

Back 24

a marine fossil now extinct

Front 25

Archean

Back 25

oldest era in geologic time, no evidence of life

Front 26

Cambrian

Back 26

time when fossils are preserved because of hard parts

Front 27

Trilobite

Back 27

a marine organism that lived only in the Paleozoic Era. It is an index fossil for that era

Front 28

Precambrian

Back 28

began 2.5 billion years ago, contains simple life in the oceans, no life on land

Front 29

dinosaur

Back 29

terrestrial reptile that developed an upright posture and dominated the Mesozoic land

Front 30

altered hard parts

Back 30

fossils whose organic material has been removed and whose hard parts have been changed by recrystallization or mineral replacement

Front 31

cast

Back 31

fossil formed when an earlier fossil of a plant or animal leaves a cavity that becomes filled with minerals or sediment

Front 32

cross-cutting relationships

Back 32

principle stating that a fault or intrusion is younger than the rock it cuts across

Front 33

eon

Back 33

longest time unit in the gological time scale , measured in billions of years

Front 34

gasohol

Back 34

biomass fuel that is a mixture of gasoline and ethanol and can be used in conventional gasoline engines

Front 35

geothermal energy

Back 35

energy produced from Earth's own internal steam and hot water

Front 36

mold

Back 36

fossil that can form when a shelled organism decays in sedimentary rock and is weathered away leaving a hollowed-out impression

Front 37

original horizontality

Back 37

principle stating that sedimentary rocks are deposited in horizontal or nearly horizontal layers

Front 38

original preservation

Back 38

describes a fossil with soft and hard parts that have not undergone any changes since the organixam's death

Front 39

permineralization

Back 39

process in which pore spaces in a fossil are filled in with substances

Front 40

photovoltaic cell

Back 40

thin transparent waters that convert sunlight into electrical energy and are made up of layers of born and phosphorus enriched silicon

Front 41

radioactive decay

Back 41

emission of atomic particles at a constant rate from a radioactive substance and its resulting change into other elements over time

Front 42

superposition

Back 42

principle stating that in an undisturbed rock sequence, the oldest rock layer are at the bottom and each successive layer is youger than the layer beneath