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90 Cards in this Set
- Front
- Back
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What did people notice when they studied new world maps 400 years ago? |
The continents fit together like a jigsaw puzzle. |
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The German scientist Alfred wegener proposed a hypothesis now called what? |
Continental drift. |
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Wegener hypothesized that the continents formed part of a single land mass or what? |
A supercontinent. |
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Why was wegener interested in finding fossils of the same plants and animals on two different continents? |
Because in places that were joined fossils in the same area should be the same. |
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How did the ages and types of rocks found in some coastal areas of Africa and south America support wegeners hypothesis? |
They matched closely. |
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What do layers of debris from ancient glaciers in southern Africa and south America indicate to geologist? |
That they were the same as they are now. |
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What evidence shows that tropical or subtropical swamps used to cover areas that now have colder climates? |
Plant fossils. |
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Undersea mountain ranges with steep, narrow valleys in the center are called what? |
Mid-ocean ridges. |
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Compared to sediment found farther from a ridge, sea floor sediment closer to a ridge is what? |
Thinner. |
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Compared to rocks farther from a ridge, rocks closer to a ridge are what? |
Younger. |
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What is sea floor spreading? |
The mechanism that causes the continents to move. |
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What is a folded mountain? |
A mountain formed when rocks layers are squeezed and uplifted. |
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What is a fault block mountain? |
Forms where faults break earths crust into large blocks that tilt and drop. |
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What is a dome mountain? |
Mountain with rock layers sloping from a central point. |
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What is a fault? |
A break in rock where surrounding rock slides. |
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What happens when continental and oceanic lithospheres collide? |
The oceanic lithosphere subducts beneath the continental lithosphere. |
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What happens when two oceanic plates collide? |
The denser plate subducts beneath the other plate. |
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When to continents collide, what happens? |
The resulting uplift can form mountains. |
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Where do volcanic mountains commonly form? |
Along convergent plate boundaries. |
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The theory that explains why and how continents move is called? |
Plate tectonics. |
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What is oceanic crust? |
Dense crust made of rock that is rich in iron and magnesium. |
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What is continental crust? |
Low density crust made of rock that is rich in silica. |
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What are tectonic plates? |
Blocks of Earth's she'll that ride on a deformable layer of the mantle. |
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What is the lithosphere? |
The solid outer layer of Earth, that consists of the crust and the rigid upper part of the mantle. |
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What is the asthenosphere? |
Solid, plastic layer of the mantle beneath the lithosphere. |
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A sudden movement along the boundary of a tectonic plate is what? |
Earthquake. |
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A zone of active volcanoes that encircles the Pacific Ocean is known as what? |
Pacific ring of fire. |
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What is a divergent? |
A boundary between tectonic plates that are moving away from each other. |
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What is a convergent? |
The boundary between tectonic plates that are colliding. |
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What is a transform? |
Boundary between tectonic plates that are sliding past each other horizontally. |
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What is a mid ocean ridge? |
Undersea mountain range. |
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What happens to magma at divergent boundaries? |
Magma rises to the surface. |
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When oceanic lithosphere collides with continental lithosphere, the oceanic lithosphere is more dense than the continental lithosphere, so it does what? |
Sinks or subducts. |
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What happens when two plates made of continental lithosphere collide? |
Neither plate subducts, the colliding edges crumple and thicken which causes uplift that forms large mountain ranges. |
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What happens when 2 plates made of oceanic lithosphere collide? |
One plate subducts under the other plate and a deep ocean trench forms. |
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What causes earthquakes at transform boundaries? |
The two plates slide horizontally past each other. |
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How are transform boundaries different from other types of boundaries? |
Transform boundaries do not produce magma. |
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What is an example of a transform boundary? |
The San Andreas fault. |
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The movement of heated material due to differences in density is called what? |
Convection. |
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What happens to newer, warmer rock at a mid ocean ridge as it cools? |
It is elevated above nearby rock. |
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Define earthquake? |
Movements of the ground that are caused by a sudden release of energy when rocks along a fault move. |
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What is a fault? |
A break in a body of rock along which one block slides relative to another. |
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The trembling and vibrations of an earthquake are caused when what happens? |
The stress becomes so great that the rocks of a fault suddenly grind pass each other. |
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The sudden return of elasticity deformed rock to its undeformed shape is called what? |
Elastic rebound. |
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The location within earth along a fault where the first motion of an earthquake occurs is called what? |
The focus. |
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Define epicenter . |
The point on earths surface directly above the focus. |
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When rocks along a fault slip into new positions, they release energy in the former of vibrations called what? |
Seismic waves. |
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Where do seismic waves travel? |
Outward in all directions from the focus through the surrounding rock. |
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What's a body wave? |
A seismic wave that travels trough the body of a medium. |
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What is a surface wave? |
A seismic wave that travels along the surface of a medium. |
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What is a P wave? |
The fastest seismic wave; causes particles of rock to move in a back and forth direction parallel to the direction in which the wave is traveling, can travel through solids,liquids, and gasses. |
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What is a Saturday wave? |
The second fastest seismic wave, causes particles of rock to move in a side to side direction perpendicular to the direction in which the wave is traveling, can only travel through solids. |
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What are two other names for President waves? |
Primary or compression waves. |
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What are two other names for S waves? |
Secondary or shear waves. |
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What are the two types of surface waves called? |
Love waves and Rayleigh waves. |
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Rock moves in what way as a result of love waves. |
Rocks move side to side and perpendicular to the direction in which the waves are travelling. |
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The ground moves in what way as a result of Rayleigh waves. |
The ground moves with an elliptical, rolling motion. |
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What is the study of earthquakes and seismic waves called? |
Seismology. |
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A tracing of earthquake motion that is recorded by a seismograph is called what? |
Seismogram. |
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Why are P waves the first waves to be recorded by a seismograph? |
P waves travel faster than s waves. |
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Which type of wave is the second wave to be recorded by a seismograph? |
S waves. |
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What types of waves are the slowest, therefore the last to be recorded by a seismograph? |
Surface, Rayleigh, or love waves. |
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Scientists determine the distance to an epicenter by analyzing what? |
The arrival times of P waves and the S waves. |
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Before computers were widely available, how did scientist locate the epicenter of an earthquake? |
On a map, they Drew circles around at least 3 seismograph stations that recorded vibrations from the earthquake. |
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What's magnitude? |
The measure of the strength of an earthquake. |
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What's the Richter scale? |
A measurement system that beset earthquake strength on ground motion. |
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What is moment magnitude? |
The measure of earthquake strength based on the size of the area of the fault that moves, the average distance that the fault block moves, and the rigidity of the rocks in the fault zone. |
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What's intensity? |
The amount of damage caused by an earthquake. |
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What's the mecalli scale? |
A measurement system that expresses earthquake intensity in Roman numerals and describes the effects of each intensity. |
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Magma rises upward through crust because... |
The magma is less dense than surrounding rock. |
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Lava flows from an opening in Earth's surface called what? |
A vent. |
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What's lava? |
Magma that flows onto earths surface, the rock that forms when lava cools and solidifies. |
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What is a volcano? |
A vent or fissure in Earth's surface through which magma and gasses are expelled. |
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A major zone of active volcanoes encircling the Pacific Ocean is called what? |
The Pacific ring of fire. |
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The Pacific ring of fire is also one of Earth's major what? |
Earthquake zones. |
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Many volcanoes are located along what? |
Subduction zones. |
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One tectonic plate moves under another along a... |
Subduction zone. |
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Magma or igneous rock that is rich in feldspar and silica and is generally light in color is called what? |
Felsic. |
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Magma or igneous rock that is rich in magnesium and iron and is generally dark in color is called what? |
Mafic. |
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Mafic rock commonly makes up what? |
Oceanic crust. |
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Felsic rock commonly makes up what? |
Continental crust. |
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The force of a volcanic eruption is affected by what? |
The viscosity of magma. |
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Mafic magmas, with low viscosity and runny lava cause what? |
Quiet eruptions. |
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Felsic magmas, with high viscosity and sticky lava, cause what? |
Explosive eruptions. |
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Explosive eruptions are most likely caused by magma with what? |
Large amounts of trapped, dissolved gases. |
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Oceanic volcanoes commonly form from what? |
Mafic magma. |
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Eruptions from oceanic volcanoes are usually what? |
Quiet eruptions. |
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What's a shield volcano? |
A volcanic cone that is broad at the base and has gentle sloping slides. |
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What is a cinder cone? |
Volcano with very steep slopes that are rarely more then a few hundred meters high and have angles close to 40 degrees |
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Composite volcano? |
Volcano made of alternating layers of hardened lava flows and pyrclastic material. |
