ES Unit 2

The Movers and Shakers

abyssal plains

Long, flat stretches of the ocean floor.

accretionary wedge

A build-up of sediment that is scraped off the oceanic crust as that crust subducts.

active margin

Continental margin where subduction occurs.

Aleutian-type mountains

Mountains that form when oceanic plates collide.

Andean-type mountains

Mountains that form from oceanic crust colliding with continental crust.

arc-continent mountains

Mountains that are formed by terrane accretion.

atolls

Coral reefs that form around volcanic islands.

buoyancy

The force that causes floating.

chemoautotroph

An organism that makes food from chemical reactions.

continental margin

Where a continent meets an ocean.

continental rise

The gradual decline at the end of a passive margin.

continental shelf

The submerged, relatively flat land at the edge of a shoreline where a continent meets the ocean crust.

continental slope

The steep part of the continental margin.

coral reefs

An underwater structure made of coral that supports marine life.

deform

Alter the shape of something by stress.

fault-block mountain

Mountains formed by normal faults (two plates under tension).

faulting

When the crust breaks due to plate movement.

folding

When rocks bend due to compression.

guyots

Underwater volcanoes with flat tops.

isostasy

The balance between buoyancy and gravity.

isostatic adjustment

When the balance between buoyancy and weight changes.

mountain

Any land that rises sharply compared to the land around it.

mountain belt

Several parallel mountain ranges.

mountain range

A string of mountains.

orogenesis

The process of mountain formation.

passive margin

Continental margin that has no subduction.

rift zones

Where seafloor spreading happens.

seamounts

Underwater mountains.

shelf break

Where the shelf meets the slope.

sonar

Sound waves that are used to determine the distance to an object.

submarine canyon

A canyon cut out of the continental slope.

terrane

A patch of land that differs in origin from its neighbors on the continent.

terrane accretion

When a terrane is added to a continent due to plate movement.

topography

The features and elevation of the land surface.

active volcano

A volcano that has erupted in the last few hundred years.

aftershocks

Smaller earthquakes that happen after the big slip.

caldera

A depression that forms when a volcano collapses into itself.

central vent

The direct route from the magma chamber to the volcano peak.

cinder cone volcanoes

Small volcanoes that are made of cinders.

composite cone volcanoes

Volcanoes with sharp peaks and violent eruptions.

crater

The bowl-shaped depression at the top of a volcano.

dormant volcano

A volcano that hasn't erupted recently but could in the future.

epicenter

The part of Earth's surface directly above the focus of an earthquake.

extinct volcano

A volcano that scientists think will never erupt again.

focus

The place on the fault that first slips in an earthquake.

foreshocks

Small slips before a large earthquake.

intensity

A measure of the strength of an earthquake that depends on where the measurement was taken.

L (Land) waves

Seismic waves that travel on land.

lava

Magma that erupts onto Earth's surface.

lava dome

A volcano that forms from very viscous magma at the peak of another volcano.

liquefaction

The ground becomes fluid, like quicksand.

magma

Molten or partially molten rock that lies below Earth's surface.

magma chamber

Chamber where molten rock resides.

magnitude

Describes the overall strength of an earthquake, regardless of where it occurred.

P (Primary) waves

The fastest seismic waves. P waves can travel through both rock and liquid.

pyroclastic flow

Flows that contain high-density mixtures of hot, dry rock fragments and hot gases.

Richter scale

The scale used to measure the magnitude of an earthquake.

S (Shear) waves

A type of seismic wave that moves side to side and can travel through rock but not liquid.

seismometers

Devices used to detect seismic waves.

shield volcanoes

Low volcanoes with gradual slopes and peaceful eruptions.

side vents

Cracks in the side of a volcano.

tephra

Solid material ejected by a volcano.

tsunami

A giant wave caused by an underwater volcano eruption or earthquake. From the Japanese word meaning “harbor wave.”

viscosity

The resistance of a liquid to movement and flow.

abrasion

When one rock fragment strikes another and they break.

advancing

A glacier that is growing faster than it is melting.

alpine/valley glaciers

Small glaciers that form in valleys.

avalanche

A mass of ice and snow falling down a hill very fast.

basal slip

The way an entire glacier slips down a hill.

carbonation

The breakdown of rocks by carbonic acid.

cave

An underground hole.

caverns

Very large systems of caves.

chemical weathering

Breaking rock down by changing its chemical composition.

cirques

Armchair-shaped valleys.

crevasse

A crack that forms on the top of a glacier.

drumlins

Smooth, egg-shaped hills.

erosion

The wearing away of land by water or wind; when soil and rock is moved from its original location.

erratics

Big rocks that have been deposited by glaciers into an area with a different type of rock.

eskers

Long winding ridges of sand and gravel.

firn

Compacted snow that is on its way to becoming glacial ice.

fjords

Very deep cuts that act as inlets to the ocean.

frost wedging

When water expands inside a crack in a rock, breaking the rock.

glacial drift

Stuff deposited by glaciers.

horn peaks

Large peaks around a group of cirques.

hydration

The breakdown of rocks as they absorb water.

hydrolysis

The reaction of water with something.

ice sheets

Enormous glaciers that can cover entire continents.

karst topography

Features that form due to the chemical weathering of limestone.

kettles

Large holes left behind by glaciers.

limestone pavement

An area of flat limestone that has been chiseled away by chemical weathering and is now exposed at Earth's surface.

mass wasting

The downward movement of rock or soil due to gravity.

moraines

Piles of boulders, rocks, pebbles, and clay left behind by a glacier.

mudflow

A very fast movement of rock and soil down a steep slope saturated with water.

oxidation

When oxygen reacts with something (often called rusting).

physical weathering

Breaking rock into smaller and smaller pieces, mostly by force.

plastic flow

When ice has enough pressure to flow through the center of the glacier.

retreating

A glacier that is melting faster than it is growing.

roche moutonnées

Mountains that are rough on one side and smooth on the other.

rockslide

When a mass of rocks break loose and slide down a slope rapidly.

sinkhole

A depression in the ground caused by dissolving of underlying limestone, salt, or gypsum.