Relative age
Index fossils
Rock A is older than
Rock B and younger
than Rock C
Absolute Age
Rock A is 2.6 billion
years old
A fossil that only lived
Says that rocks that are
during a certain time
on the bottom are the
period (ex. Trilobite)
Law of
oldest and rocks on the
that can help us find the Superposition
top are the youngest if
age of a rock that has
not disturbed
the fossil in it.
Half life
How long it takes for
half of the radioactive
element to decay into
the stable element (ex.
Uranium changing to
Lead)
Radioactive
dating
(radiometric
dating)
Used to figure out how
old a rock is. See how
much of the parent
element is still left.
Preserved
remains
A fossil of a dead animal
that has been trapped
in ice, amber or tar.
Carbon
dating
Used to see how old
bones, teeth, wood and
things that were once
alive are (not good for
dating rocks)
Trace fossils
A fossil of a footprint,
nest, eggs, burrow of an
organism that once
lived
Petrified
fossil
A fossil in which
minerals have seeped in
and replaced part or all
of the organism.
Intrusion
Magma came up and
cut through a rock. It is
younger than the rock it
cut through.
Vertebrate
Animal that has a
backbone
Invertebrate
Animal that does not
have a backbone
Cenozoic
Age of Mammals, Era
you live in
Mesozoic
Age of Reptiles
Quaternary
Time period you live in
Paleozoic
Era that had
invertebrates,
amphibians, land
plants, insects and
some reptiles
PreCambrian
Time
Long period of history
of where Earth was
formed and Earth’s
atmosphere
Unconformity
Gap in the geologic
record where erosion
wiped away some of
the layers of rock
Amphibians
Animals that live partly
in the water and partly
on land
Mammals
Warm blooded
vertebrates
4.6 billion
years
How old the Earth is
Igneous
rocks
Radioactive dating
works best with which
types of rocks?
Sedimentary
rocks
The Law of
Superposition works
best with which types of
rocks?
Single celled
organisms
The first type of things
that lived on Earth
during the Precambrian
Time
Hydrogen &
Helium
The gases in Earth’s first
atmosphere – blown
away by solar winds
Comets
What brought water
vapor to Earth and
caused rain which
accumulated in our
oceans
Mass
Extinction
When all the animals or
plants die
Evolution
How animals and plants
change over long
periods of time
Fossils
The remains or traces of
an organism that lived
in the past.
Precambrian Time
Paleozoic Era
Mesozoic Era
Cenozoic Era
Quaternary Period
Permian Period
Carboniferous Period
Mass extinction of ocean and
land animals
Reptiles, ferns, trees
Devonian Period
Fish, amphibians
Cambrian Period
Explosion of life on Earth –
invertebrates in the sea
Silurian Period
Insects and plants on Land
Ordovician Period
Triassic Period
First dinosaurs, reptiles
Jurassic Period
Dinosaurs, first birds
Cretaceous Period
Paleogene, Neogene Periods
Mammals and grasses
Extinction of dinosaurs, first
flowers and fruit
Humans, pets
Formation of earth,
atmosphere, ocean, continents
invertebrates /
vertebrates/jawless fish
Age of Reptiles
Age of Mammals
First Era