Earth Science Vocab Review

All of the vocab from the Earth Science Units

crust

the outermost layer of the Earth

mantle

the layer of the Earth between the crust and the core

core

extends from the bottom of the mantle to the center of the Earth

lithosphere

the rigid outer part of the earth. it's made up of the crust and upper mantle.

asthenosphere

The soft layer of the mantle on which the lithosphere floats.

mesosphere

is below the asthenosphere and is the strong lower part of the mantle

outer core

the liquid layer of the Earth's core that lies beneath the mantle and surrounds the inner core

inner core

the solid, dense center of our planet that extends from the bottom of the outer core to the center of the Earth

density

the amount of matter in a given space (\=mass/volume)

radioactive decay

The breakdown of a radioactive element, releasing particles and energy

convection

The transfer of thermal energy by the circulation or movement of a liquid or gas

continental drift

The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations

seafloor spreading

The process that creates new sea floor as plates move away from each other at the mid-ocean ridges

Pangea

A supercontinent containing all of Earth's land that existed about 225 million years ago.

Alfred Wegener

A German scientist who proposed the theroy of continental drift

Lithosphere

A rigid layer made up of the uppermost part of the mantle and the crust. The plates that we see move around.

Asthenosphere

The soft layer of the mantle on which the lithosphere floats.

Paleomagnetism

The study of the alignment of magnetic minerals in rock, specifically as it relates to the reversal of Earth's magnetic poles

divergent boundary

A plate boundary where two plates move away from each other.

transform boundary

A plate boundary where two plates slide past each other in opposite directions

Subduction

One plate going under another plate. How old rock gets "recycled".

trench

extremely deep areas in the ocean that are created by a subducting plate

mid-ocean ridge

An underwater mountain chain where new ocean floor is formed

convergent boundary

A plate boundary where two plates come together or collide.

earthquake

The shaking that results from the movement of rock beneath Earth's surface.

fault

A break or crack in Earth's crust along which the rocks move.

focus

The point beneath Earth's surface where rock breaks under stress and causes an earthquake

Epicenter

the point on the Earth's surface directly above the focus of an earthquake

elastic rebound

the sudden return of elastically deformed rock to its undeformed shape that causes a release in energy we call an earthquake

deformation (of rocks)

when rocks change shape because of stress

seismic waves

vibrations that travel through Earth carrying the energy released during an earthquake

compression

Stress that squeezes rock until it folds or breaks

tension

Stress that stretches rock so that it becomes thinner in the middle

shear

stress that pushes masses of rock in opposite directions causing a sideways movement

P waves (Primary waves)

A type of seismic wave that travels through liquids and solids. they push and pull. they are faster and arrive first

S waves (secondary wave)

A type of seismic wave that travels through only solids. they move the ground up and down or side to side. they are slower and arrive second.

folding

the bending of rock layers due to stress

Anticline

A fold in rock that bends upward into an arch

Syncline

A fold in rock that bends downward to form a valley

Monocline

A fold in rock layers in which both ends of the rock remain horizontal

Stress

The amount of force on an object. For this unit we mean force on rock.

Law of Superposition

states that younger layers of rock are deposited on top of older layers.

Law of Cross Cutting

states that any feature that cuts across a rock or layer must be younger than the rock or layer it cuts across

Law of Inclusions

states that an inclusion (fragment of another rock) must be older than the rock it is enclosed in

Law of Unconformities

states that missing rock layers show missing time. These are caused by erosion and usually shown with a wavy line

Law of Uniformitarianism

states that things and processes happened in the past the same way they happen in the present.

The Principle of Folding

states that folding always happens after the layers have been deposited. Caused by tectonic activity and compression stress.

Weathering

the process that breaks down rock and other materials at Earth's surface

Erosion

The process by which wind, water, ice, or gravity transports soil and sediment from one location to another

Mechanical weathering

The type of weathering in which rock is physically broken into smaller pieces

Frost wedging

the cracking of rock by the expansion of water as it freezes in crevices and cracks

Thermal expansion and contraction

repeated heating and cooling of materials cause rigid substances to crack and separate

Exfoliation

The process by which the outer layers of rock slowly peel away due to pressure changes

Abrasion

The grinding away of rock by other rock particles carried in water, ice, or wind

Plant wedging

the cracking of rock by expanding root systems of a plant as it grows into the rock

Chemical weathering

the process by which rocks break down as a result of chemical changes

Dissolution

when rock dissolves into water (often containing acid)

Oxidation

when minerals combine with oxygen to form new substances which may be weaker.

Hydrolysis

when materials combine with water to form new substances which may be weaker.

Permeable

a substance that it is full of holes so that water or air can pass through it.

Sediments

Loose materials such as rock fragments, mineral grains, and bits of shell that have been moved by wind, water, ice, or gravity

Alluvial fan

A wide, sloping deposit of sediment formed where a stream leaves a mountain range

Delta

A landform made of sediment that is deposited where a river flows into an ocean or lake

Mass movement

the movement of a large mass of sediment or a section of land down a slope

Moraine

a mass of rocks and sediments deposited by a glacier

Deposition

Process in which sediment is laid down in new locations.

relative dating

Any method that determines the age of rock or fossils compared to another rock or fossil.

absolute dating

any method that allows scientists to date the exact age of a rock or fossil.

Inference

A conclusion reached on the basis of evidence and reasoning

Law of Superposition

The geologic principle that states that each layer is older than the layer above it and younger than the layer below it.

Intrusion

magma that has pushed into cracks in existing rocks

Faulting

a crack in the earth's surface where two pieces of land have moved in different directions

Unconformity

A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time.

radioactive decay

the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element

Isotope

Atoms of the same element that have different numbers of neutrons

Parent isotope

the atom that undergoes radioactive decay in a nuclear reaction

Daughter isotope

A more stable atom that results from the decay of a radioactive atom.

half-life

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

Carbon-14

An isotope of carbon used to date objects less than 70,000 years old.

Uranium-238

An isotope of uranium used to date the age of the Earth at approximately 4.5 billion years

index fossil

fossils of widely distributed organisms that lived during only one short period

body fossil

A fossil that consists of the preserved body of an animal or plant or an imprint of the body

trace fossil

A type of fossil that provides evidence of the activities of ancient organisms

chemical fossils

Traces of organic chemicals that indicate former life

Fossil

A trace of an ancient organism that has been preserved in rock.

artifact

an object made by a human being, typically an item of cultural or historical interest.

archaeologist

a scientist who learns about ancient people by studying the things they left behind

Paleontologist

A scientist who studies fossils to learn about organisms that lived long ago