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Earth History VOCABULARY

Earth History Vocabulary - 8.E.2
Mold Fossils
Cast Fossils
Petrified Fossil
Carbonized Fossil
Preserved remains or
traces of animals, plants,
and other organisms from
the remote past
Formed when an object is
placed into soft mud and is
removed by decomposition
or physical sources
Formed when a mold fossil
fills up with sediment; three
“Turned to stone”, a fossil
in which minerals replace
all or some of an organism.
The remains of plants,
animals and other
organisms are converted
into a carbon or
carbon-containing residue
Preserved Fossil
Trace Fossil
Relative Age
Index Fossil
A plant, animal or other
organism that is perfectly
preserved for many years
Evidence of plants,
animals, and other
organisms in the form of
preserved footprints,
tracks, burrows, borings,
and feces left behind rather
than the actual organism’s
The geologic age of a
fossil organism, rock or
geologic feature or event
defined relative to other
organisms, rocks, or
features or events rather
than in terms of years
Fossils that are used to
define and identify geologic
time periods
A group of extinct
segmented hard shelled
marine arthropods that
lived over 520 million years
the concept that the earth's
surface was shaped in the
past by gradual processes,
such as erosion, and by
small sudden changes,
such as earthquakes, like
the processes we see
today rather than by
sudden catastrophic acts
Law of
Absolute Age
The theory that major
changes in the earth's
crust result from sudden
catastrophes, such as the
impact of a large meteor,
rather than from gradual
evolutionary processes.
A gap in the sequence of
rock layers; The surface
where new rock layers
meet a much older rock
surface beneath them
A geological law that states
in any undisturbed
sequence of rock layers
the youngest layer is on
the top and the oldest layer
is on the bottom
The true age of a rock or
Geologic Time
Precambrian Era
Mesozoic Era
The time taken for the
radioactivity of a specified
isotope to fall to half its
original value
The rate of decay of
unstable isotopes can be
used to estimate the
absolute ages of fossils
and rocks
A system that divides
Earth’s history into
intervals of time defined by
major events or changes
on Earth.
The era of time prior to 600
million years ago, covering
90 % of Earth’s history
divided into three eras:
Hadean, Archaean, and
An interval of time known
as the age of the reptiles
from about 252 to 66
million years ago
Cenozoic Era
An era that spans about 65
million years ago also
known as the age of the
The era, which ran from
about 542 million years to
251 millions years ago,
known for great change on
Earth with plants becoming
widespread and the first
vertebrate animals
colonizing land. Also
known for the breaking up
of a supercontinent and the
formation of another
The process of becoming
extinct where a species
comes to an end or dies
A radioactive isotope which
is present in organic
materials and is the basis
for radiocarbon dating
Geologic Column
Ice Cores
Rock Cycle
The theoretical
classification system for
the layers of rocks and
fossils that make up the
Earth’s crust.
A core sample of ice
removed from an ice sheet
most commonly in the
polar ice caps of
Antarctica; provides
information on climate from
different periods (up to
almost one million years)
that can be used for
A continuous process by
which rocks are created,
changed from one form to
another, destroyed, and
then formed again.
A break or fracture in the
ground that occurs when
the Earth's tectonic plates
move or shift and are
areas where earthquakes
are likely to occur.
Rock formations from
magma that cools and
solidifies within the crust of
the planet
Rock formations from
magma that cools and
solidifies above the surface
of the crust
Rock that has formed
through the deposition and
solidification of material,
especially material
transported by water
One of the three main rock
types and formed through
the cooling and
solidification of magma or
Rocks that are subjected to
high heat and pressure
which causes a profound
change in form
Atoms of the same
element that have the
same number of protons
but different numbers of