Earth Mechanics Flashcards
Continental Crust
Crust that defines the landmasses (continents) on Earth. Usually older and less dense than the oceanic crust.
Oceanic Crust
The crust that supports the world’s oceans. It is relatively thinner and denser than continental crust.
Mantle
The mantle is the semi-solid, thickest layer between the crust and the core. The mantle contains iron and nickel, whose flow produces the Earth’s magnetic field.
Outer Core
The outer core is the upper half of the core region and the only liquid layer, also composed of iron and nickel.
Inner Core
The inner core is the hottest layer, found at the very center of the Earth. Pressures here are so extreme that it is solid, and its temperatures reach 5200 degrees celsius, equivalent to temperatures on the surface of the sun.
Magma
Magma is molten rock located under the Earth’s surface.
Lava
Lava is the term for magma flowing on the Earth’s surface.
Molten
(adj) To be melted by heat.
Density
Density is how compact something is. It is the quantity of something per unit volume, unit area, or unit length.
Geologic Continent
There are 6 geologic continents: Africa, Eurasia, North America, South America, Antarctica, and Australia). They are not defined by country borders, language, culture, or race/ethnicity, but by geologic features.
Continental Drift
Is the process by which continents are moving across the Earth’s surface over time.
Fossil
A fossil is the remain/impression of a prehistoric creature (as of today).
Glacier
A glacier is a flowing river of ice. They are found in cold regions, such as the poles, and are responsible for weathering and carving landscapes in many places.
Ice Age
The Ice Age is a long period of time when global temperatures shift to the colder range, causing the poles to expand towards the equator.
Land Mass
A land mass is a large body of land, such as a continent.
Pangaea
Pangaea was the supercontinent (had all of today’s continents) that existed about 300 million years ago.
Supercontinent
A supercontinent (such as Pangaea) was a large continent that typically was composed of several modern-day continents.
Alfred Wegner
Alfred Wedner was a scientist who first proposed that all of Earth’s continents were once combined into a supercontinent named Pangea.
Plate Tectonics
Is the theory that Earth’s crust is divided up into large sections, called plates, that are constantly moving and interacting with each other.
Divergent Boundary
The point where two tectonic plates are moving away from each other. Earthquakes here are common, and magma rises from the Earth’s mantle to the crust, creating an oceanic crust.
Convergent Boundary
The point where two tectonic plates are colliding. Depending on the density of the plates, one might submerge beneath the other, or both will force up into a mountain range.
Transform Boundary
Points where two tectonic plates are sliding past each other. As they rub against each other, a huge amount of pressure can build up, causing earthquakes.
Seafloor Spreading
Is when tectonic plates (oceanic) spread apart from each other because of convection in the mantle. The new material comes up to fill in the gaps left behind, creating a new oceanic crust. One example of sea-floor spreading is the mid-Atlantic ridge.
Boundary
Is where two tectonic plates meet.
Geological Feature
Is a feature of the Earth, such as a mountain range.
Hot Spot
This is where volcanic activity is common. This is usually due to the volcano being situated on top of a fault line, or being under a large plume of magma.
Rift
When a plate is being pushed away from the divergent boundary.
Fault Lines
The borders of tectonic plates. Earthquakes are common around these lines.
Hydrothermal Vent
A fissure in the seabed from which geothermally heated water escapes.
Ocean Trench
Is a deep and narrow depression in the ocean floor. They are common at convergent boundaries.
Earthquake
An earthquake is when the crust suddenly shakes violently, varying in intensity, caused by the growing tensions between two plates.
Epicenter
The epicenter is the point on the Earth’s surface that is directly above the starting point of an earthquake.
Fault
A fault is an extended fracture between two slabs of rock. Rocks on either side of the fault move relative to each other, really slowly, and can sometimes release their energy in the form of an earthquake.
P-wave
A P-wave is a type of body wave, a seismic wave that travels through the Earth’s interior. They were the first waves to reach a seismograph (that’s how they got their name– P as in primary). They travel around 6/7 km/s.
S-wave
An S-wave is another type of body wave, slower than a P-wave (S for secondary).
Seismic Wave
Seismic waves are waves of motion that radiate from the focus of an earthquake. They compress and squeeze material, then release them again, traveling very rapidly.
Seismograph
A seismograph is a device that responds to ground noise and shaking caused by earthquakes, volcanic eruptions, and explosions.
Tsunami
A tsunami is a large wave caused by the displacement of a large body of water, or by underwater earthquakes and/or volcanic activity.
Strike-Slip Fault
Strike-slip faults are vertical fractures where slabs of rock have mostly moved horizontally.
Dip-Slip Fault
A dip-slip fault is an inclined fracture between two slabs of rock, where the rock mass above the fault slides down.
Compression
Compression is when tectonic plates are squeezed/pushed together, making the crust shorter and thicker.
Tension
Tension is the stress tectonic plates experience as they are being pulled apart, making the crust longer and thinner.
Shearing
Shearing is when an area of rock has become deformed due to different stresses. These rocks can come in all sorts of formations and patterns.
