STEM Plate Tectonics Unit 4 Test

Geologists

Scientists who study Earth wanting to know about the materials that Earth is made of and how Earth has evolved during its history

Earth's Crust

Earth's outermost layer that is thicker under the continents and thinnest under the oceans. Continental crust is mostly granite and Oceanic crust is mostly basalt.

Continents

Large land masses

Earth's Mantle

Thickest layer of the Earth between the Earth's crust and the outer core. It is composed of rock that contains iron and magnesium. It makes up most of Earth's mass. The upper part is rigid and the lower part flows slowly.

Earth's Core

The center of the Earth which is composed of iron and nickel. It is made up of two parts.

Inner Core:

The solid part of Earth's core which is the hottest layer and composed of iron.

Outer Core:

Liquid part of Earth's core which flows slowly and is composed of metal.

Conduction:

The transfer of heat energy through solid matter while one particle strikes another. Example: When heat moves through Earth's crust.

Convection: (How heat moves on mantle)

The transfer of heat energy by flowing material such as a liquid or gas. For example, when hot air rises, making cooler air come in and be heated.

convection current

As matter in the lower mantle is heated, it expands, becomes less dense, and is pushed upward by the cooler, denser material around it. It is also a cycle of heated matter due to density differences. It is demonstrated as a current in a fluid that results from convection.

Fossils

The remains, imprints, and traces of once living things.

Pangaea

A giant supercontinent called "Pangaea" which means "all lands." It existed during the late Palezoic and early Mesozoic times.

Continental Drift

The idea that continents move from one part of the Earth to another. The once supercontinent, Pangaea drifted apart over geologic time to their new present positions on Earth.

Lithosphere (Top part of the upper mantle)

The rigid outer layer of Earth which is solid and able to move because it is made up of moving sections/plates.

Plates

The Earth's crust is broken into 12 separate pieces called plates. Plates can be made up of both continental and oceanic crust.

Asthenosphere (Underneath the lithosphere and in the upper mantle) (lithosphere + plates go with it)

Even though it is solid, it is hot enough to bend and change shape. It causes the shapes, positions and sizes of the continents to change.

Plate Tectonics

The theory that explains how and why the plates move.

Sonar Mapping

Ships bounce sound waves off the ocean floor which calculates the depth of the ocean in that area. To calculate the depth, they watch the time between sending the sound and recieving its echo. Sonar mapping can also be used to map the ocean floor.

Mid-ocean ridge (Underwater Volcano)

An long, narrow, underwater mountain range rising from the ocean floor. This is where new crust forms.

Rift

A valley that runs along the crest of the mid-ocean ridge. Large amounts of heat flow from it.

Magma

Melted rock

Trenches

Narrow, deep regions of the ocean floor at the edges of plates. Old oceanic crust is carried down into the mantle as one plate is forced under another.(Goes with subduction)

Subduction

The sliding of one plate under another. The subducted crust falls/sinks into the mantle and melts.(Occurs at trenches)

sea-floor spreading

The process of oceanic crust being created at the mid-ocean ridge, moving sideways away from the ridge and plunging into the mantle at trenches. (Led scientists into developing the plate-tectonic theory)

Divergent boundary

Where 2 plates are moving apart from eachother. It is found along the mid-ocean ridge and is where new crust forms. It can slowly rip apart continents.

Convergent Boundary (3 scenarios)

Where two plates come together and collide. What happens at a convergent boundary depends on the types of crust that meet. Scenario \#1 Continental Crust vs Oceanic Crust \= A trench
Scenario \#2 Oceanic Crust vs Oceanic Crust \= A trench
Scenario \#3 Continental Crust vs Continental Crust \= A mountain

Transform Boundary

Crust is neither created nor destroyed. Plates just slide past each other. (Where most earthquakes occur)

Isostasy

The balancing of the downward force of the crust and the upward force of the mantle.

Fault

A crack in the earth's crust

Ring of Fire

A circle of volcanoes surrounding the Pacific Ocean.

Earthquake

A vibration of the ground caused by rocks slipping or breaking when stress/pressure along a fault, which then triggers a release of energy

magnitude

Measure of the energy released during an earthquake. It is determined by a seismograph and compared to other earthquakes using the Richter scale.

Focus

The point in the crust or upper mantle where energy is released or where an earthquake occurs.

Epicenter

The point/location on the Earth's surface directly above an earthquake's surface. It is where surface waves move from and is determined by the distance between the arrival of p and s waves.

Richter Scale

Used to estimate the magnitude of an earthquake on a scale from 1-10. Each number on the scale is 10x the number below it.

Mercalli scale

Used to rate the amount of damage done by an earthquake in a certain location on a scale from I-X11. (Using roman numerals)

Alfred Wegener

A German scientist who proposed the theory of continental drift. Many people did not believe him when he proposed his theory, and wasn't thought of as a "real scientist."

Harry Hess

A geologist that discovered sea floor spreading using sonar mapping. His research and information helped other scientists conclude Alfred Wegener's theory and showed how sea-floor spreading was one of the main causes of Continental Drift.

Theory of Continental Drift

This theory was proposed at the beginning of the 20th century (1912) by scientist Alfred Wegener. It explained why the continents appeared to fit together like puzzle pieces. It proposes that the continents are not stationary- they actually move very, very slowly across the face of the Earth.

Theory of Continental Drift Evidence

(SMPGF)

Wegener based his theory on 5 pieces of evidence:


1. Shapes of continents fit like puzzle pieces
2. Presence of rocks of the same type/age on both sides of the Atlantic Ocean
3. Fossil remains of a reptile on opposite sides of the ocean
4. Glacial deposits of the same age and type on different continents
5. Matching mountain belts on different countries.

Theory of Continental Drift pt. 2

Many people didn't believe Wegener's theory (even with his evidence) because he did not explain how or why the continents were able to move. They also didn't think of him as a "scientist." He passed away in 1930 on an expedition to the Greenland ice sheet. His theory was still debated on even after his death. It was not until the 1960s that evidence came about which proved Wegener's "Theory of Continental Drift."