PG Chapter 14: Internal Processes

What are the main internal processes that shape the Earth's surface?

Plate tectonics, volcanism, and earthquakes.

What is plate tectonics?

The theory that describes the large-scale movement of Earth's lithosphere, which is divided into tectonic plates.

What evidence supports the theory of plate tectonics?

Fossil distribution, the fit of continental coastlines, and geological similarities across continents.

What are the three types of plate boundaries?

Divergent, convergent, and transform boundaries.

What occurs at divergent plate boundaries?

Tectonic plates move apart, leading to the formation of new crust, often seen at mid-ocean ridges.

What happens at convergent plate boundaries?

Plates collide, which can result in subduction, mountain building, or volcanic activity.

What characterizes transform plate boundaries?

Plates slide past each other horizontally, causing earthquakes.

What are the two main types of volcanoes?

Shield volcanoes and stratovolcanoes.

How do shield volcanoes differ from stratovolcanoes?

Shield volcanoes have gentle slopes and are built from low-viscosity lava, while stratovolcanoes have steeper slopes and are made from more viscous lava.

What is the relationship between volcano type and eruption style?

Shield volcanoes typically have non-explosive eruptions, while stratovolcanoes can have explosive eruptions due to higher gas content.

What is crustal deformation?

The process by which the Earth's crust changes shape due to stress, leading to folding, faulting, or fracturing.

What causes earthquakes?

Sudden release of energy in the Earth's crust due to tectonic movements, often occurring along faults.

Who proposed the theory of continental drift?

Alfred Wegener

What is the name of the supercontinent suggested by Wegener?

Pangaea

What year did Alfred Wegener publish 'The Origins of Oceans and Continents'?

1915

What evidence supports the theory of continental drift?

Fit of the continents, glacial deposits, paleoclimatic belts, distribution of fossils, matching geologic units.

What type of evidence shows glacial deposits found on continents now near the equator?

Glacial evidence from the Permian period.

What did Wegener predict about rocks preserving climate belts on Pangaea?

He predicted the presence of tropical coal deposits, tropical reef deposits, subtropical deserts, and subtropical evaporites.

Name one fossil that supports the theory of continental drift.

Mesosaurus, Glossopteris, Lystrosaurus, or Cynognathus.

What is a major criticism of Wegener's theory?

He lacked a mechanism to explain how continents could drift.

What is the lithosphere?

The uppermost mantle and overlying crust, segmented into tectonic plates.

What is the asthenosphere?

A weaker region in the mantle beneath the lithosphere.

What is paleomagnetism?

The study of the magnetic orientation of iron in cooled magma, providing a record of past magnetic fields.

How many major tectonic plates are there?

Seven major plates.

What is the significance of mid-ocean ridges?

They are associated with divergent boundaries and are sites of volcanic activity and shallow-focus earthquakes.

What happens during subduction?

One tectonic plate is forced under another into the mantle.

What geological features are associated with convergent plate boundaries?

Trenches and mountain ranges.

What is the role of mantle convection in plate tectonics?

It drives the movement of tectonic plates as hot material rises and cool material sinks.

What evidence revived Wegener's ideas after his death?

New evidence from the oceans regarding oceanic crust and tectonic activity.

What is the density comparison between oceanic crust and continental crust?

Oceanic crust is more dense than continental crust.

What is the significance of submarine earthquakes?

They are concentrated in specific areas like mid-ocean ridges and deep ocean trenches.

What occurs during oceanic-continental plate convergence?

The oceanic plate sinks due to being more dense, forming oceanic trenches and continental mountains.

What geological features are formed by oceanic-continental plate convergence?

Oceanic trenches and continental mountain ranges, such as the Cascades and Andes.

What types of earthquakes occur along oceanic-continental plate margins?

Earthquakes occur due to subduction.

What is formed along the plates during oceanic-continental convergence?

Volcanoes, specifically a continental volcanic arc.

What happens during oceanic-oceanic plate convergence?

Subduction results in the formation of undersea trenches and island volcanic arcs.

What type of earthquakes are associated with oceanic-oceanic plate convergence?

Both deep and shallow earthquakes.

What occurs during continental-continental plate convergence?

No subduction occurs; instead, huge mountain ranges are built, and volcanoes are rare.

What type of earthquakes are common in continental-continental plate convergence?

Shallow earthquakes.

What characterizes transform boundaries?

Two plates slip past each other laterally, producing shallow focus earthquakes.

What is an example of a transform fault?

The San Andreas Fault.

What significant geological event occurred 450 million years ago?

One supercontinent existed, which broke up 200 million years ago.

What is extrusive volcanism?

Volcanism that occurs on Earth's surface.

What is intrusive volcanism?

Volcanism that occurs below the surface, also known as plutonic activity.

What is the Pacific Ring of Fire?

A region with plate boundaries around the Pacific Rim, primarily consisting of subduction zones.

What percentage of all volcanoes are located in the Pacific Ring of Fire?

75% of all volcanoes.

What are mantle plumes?

Localized hot areas not associated with plate boundaries that move with the plate.

What is a hot spot trail?

A series of volcanic islands, such as the Hawaiian Islands, formed by mantle plumes.

What is viscosity in the context of magma?

The resistance to flow of magma.

How does silica content affect viscosity?

High silica results in high viscosity; low silica results in low viscosity.

What type of eruption is characterized by high silica content?

Explosive eruptions.

What type of eruption is characterized by low silica content?

Gentle eruptions.

What are the positive effects of volcanic activity?

Temporary landscape features, origin of much of Earth's water, provision of major elements for plant growth, and increased soil fertility.

What characterizes a shield volcano?

Layer upon layer of solidified lava flows with little pyroclastic material; an example is the Hawaiian Islands.

What is a composite volcano?

A volcano that emits higher silica lavas (andesite), forms symmetric steep sides, and alternates between explosive and nonexplosive lava flows.

What is a lava dome?

A mass of very viscous lava that bulges from the vent and grows by expansion from below.

What are cinder cones?

The smallest volcanic mountains, formed from basaltic magma and slopes made from pyroclastic materials.

What is a caldera?

A large basin-shaped depression formed when a volcano explodes or collapses, larger than the original crater.

What are volcanic necks?

The pipe or throat of an old volcano that has filled with solid lava.

What are the hazards of volcanic gases?

They can cause acid rain and alter global climate.

What are pyroclastic flows?

Avalanches of hot gases and material that can travel at speeds up to 100 mph.

What is a lahar?

A volcanic mud flow that results from heavy rain and/or snow melt during an eruption.

What is diatrophism?

The deformation of Earth's crust, which includes folding and faulting.

What happens during folding?

Rocks are subjected to lateral compression, resulting in upfolds (anticlines) and downfolds (synclines).

What is faulting?

The breaking of rock accompanied by displacement along zones of weakness in the crust.

What are the four primary types of faulting?

Normal, reverse, strike-slip, and oblique faults.

What is an earthquake?

A vibration in Earth resulting from sudden displacement along a fault.

What is the epicenter of an earthquake?

The point on the Earth's surface directly above the origin of the earthquake.

What is the Richter scale?

A logarithmic scale used to measure the magnitude of earthquakes.

What is the Mercalli intensity scale?

A scale that measures the shaking intensity of an earthquake based on observed effects.

What are common earthquake hazards?

Ground shaking, liquefaction of sediments, landslides, and water movements like tsunamis.

What was the strongest recorded earthquake?

The 1960 Valdivia earthquake in Chile, with a magnitude of 9.5.

What disaster occurred in Japan in 2011?

A major earthquake followed by a tsunami and nuclear disaster.

What was the impact of the 2015 earthquake in Nepal?

Significant destruction and loss of life due to the earthquake's intensity.