Physical Science Geology Unit

What geological phenomena are explained by the theory of plate tectonics?

Plate tectonics explains earthquakes, volcanoes, mountain building, and seafloor spreading.

Which layer of the Earth does the lithosphere float on?

The lithosphere floats on the asthenosphere, a weaker, ductile layer.

What evidence did Alfred Wegener use to support his theory of continental drift?

Wegener used the fit of coastlines, similar fossils, matching geological formations, and mountain range alignment.

When did Alfred Wegener propose the theory of continental drift?

1912

What is the name of the supercontinent that Wegener proposed existed millions of years ago?

Pangaea

What technology significantly advanced ocean floor mapping in the 1950s?

sonar technology revolutionized oceanography by enabling detailed mapping of the ocean floor.

What geological feature is characteristic of mid-ocean ridges?

Mid-ocean ridges are sites where magma rises from the mantle

where do the Mid-ocean ridges take place

Mid-ocean ridges occur along divergent plate boundaries

Who independently proposed the theory of seafloor spreading?

Harry Hess and Robert Dietz independently proposed the theory of seafloor spreading in the early 1960s.

What is the role of subduction in the process of seafloor spreading?

Subduction balances seafloor spreading by recycling crust back into the mantle at deep ocean trenches.

What is the significance of magnetic stripes on the ocean floor?

Magnetic stripes confirm that new crust is generated at ridges and spreads outward

What is paleomagnetism?

Paleomagnetism is the phenomenon where rocks record Earth's magnetic field at the time of their formation.

What geological feature is characteristic of subduction zones?

Subduction zones are characterized by deep ocean trenches where denser oceanic plates sink.

What percentage of the world's earthquakes occur in the Pacific Ring of Fire?

90%

Which of the following is an example of a transform fault?

The San Andreas Fault

when was the Plate tectonics theory developed?

1960s

• what is the Plate tectonics theory?

a theory that explains the structure and behavior of Earth's lithosphere

what is the **Seafloor Spreading Theory?

Magma rises from the mantle at these ridges

Continental crust

**Light-colored

Oceanic crust

**Dark-colored

Igneous rocks

Form from cooling and solidification of magma or lava.

intrusive (plutonic)

*Cool slowly beneath Earth's surface (e.g.

Extrusive (volcanic)

*Cool rapidly on the surface (e.g.

Sedimentary rocks

**Form from the compaction and cementation of sediments derived from weathering and erosion.

Metamorphic rocks

**Result from existing rocks transformed by high pressure and temperature

Earth formed about 4.5 billion years ago from

a nebula.

Effusive (peaceful)

Lava flows gently from the vent

Explosive

Violent eruptions eject ash

Shield volcanoes

Broad

• **Composite volcanoes

Steep

Cinder cones

Small

Fissure eruptions

Linear cracks emitting lava.

Calderas

Large depressions formed by collapse after massive eruptions.

Minerals are

inorganic, crystalline solids with specific chemical compositions, formed through geological processes

Silicates

Contain silica tetrahedra, which are pyramid-shaped structures with one silicon atom bonded to four oxygens. These tetrahedra polymerize in various configurations, forming minerals like quartz, feldspar, and mica.

Non-silicates

Minerals without silica tetrahedra, such as oxides (e.g., hematite).

Ionic bonds

Transfer of electrons, forming charged ions (cations and anions), e.g., calcite (CaCO₃).

Covalent bonds

Sharing of electrons, forming strong bonds, characteristic of quartz and other silicates.

Seismometers and GPS stations are used to detect

ground movements and stress accumulation along faults

Earthquakes are classified by

magnitude (energy released) and intensity (shaking severity)

What does Pangaea mean?

"All land" in Greek

When did Pangaea break apart?

Wegener hypothesized that approximately 225 to 300 million years ago

paleomagnetism

a phenomenon that in the early 1960s

Subduction zones are

regions where denser oceanic plates are pushed beneath lighter continental or oceanic plates

Igneous rocks makes up about

90% of the earth's crust though you might not notice them because they're often covered by other types of rocks

Seismic waves generated by

earthquakes travel through Earth's layers at different speeds

Seismic waves' behavior helps scientists

model the composition

How long is the San Andreas Fault?

800 miles

How fast does the San Andreas Fault move compared to Haiti?

500 times larger

What region is under the most threat along the San Andreas Fault?

the bay areas/southern california

The team uses the rig to plant sensors deep into the rock embedding them [blank] down shielded from surface noise. - earthquake lecture

800 feet deep

What magnitude was the 2010 Chile Earthquake?

8.8 - the 5th largest ever recorded

How much did the coastline move during the Chile earthquake?

the coastline jumpted up 2 to 3 meters

earthquake side effect

tsunamis

Why does a tsunami swell in coastal areas?

When the leading edge of a tsunami hits a shallow shoreline

A 30 foot wave exerts a pressure equivalent to the weight of a

battle tank

Forecasting the next 8.0 or greater earthquake in Oregon or Washington is vital

but the evidence on land is hard to find. Where is the evidence?

Before the study

only 19 earthquakes in 10

After this discovery of the CT scan

what are the odds of an earthquake occurring on the Cascadia subduction zone?

A tsunami can look like a breaking wave

but what do tsunamis do that breaking waves don’t?

Imperceptible to human sense

a [blank] is taking place.

Every few years they slip with only a slight amount of shaking. It is called [blank] and it generates the silent quakes.

slow slip

Identifying slow-slip tremors could be critical in signaling larger quakes. During a slow slip

what happens to the chance of a larger earthquake?

Every time the deep plate slips

[blank] on the locked crust above.

Is there proof global clustering was a factor in 2010?

no - Seismic activity was within normal levelsWhat structure is built over the Hayward fault?

The answer to earthquake threat lies in [blank] not geology.

engineering

[blank] kill people not earthquakes.

buildings

An element is not the

smallest unit of matter

Rocks are not mostly made up of

non-silicate minerals.

Muon tomography (scanning) is not capable of

scanning a flat volcano like Campi Flagrei.

Silicates and non-silicates are

the two groups of minerals.

what does not fit the definition of a mineral?

organic

covalent bonding occurs when

atoms share electrons.

name two volcanic rocks

basalt and rhyolite

Crystallization is the

formation of minerals from magma or lava.

Extrusive Formation

Fast Cooling

Intrusive Formation

slow cooling

what are the five defining characteristics of a mineral?

Naturally Occurring

P-waves (Primary waves) are the

fastest seismic waves

S-waves (Secondary waves) are

slower then P-Waves

What are the two main factors that determine whether a volcanic eruption will be peaceful (effusive) or explosive?

The two main factors are the magma's composition (specifically its silica content) and its resulting viscosity. Magma with low silica content (mafic) has low viscosity

Mid-Ocean Ridge

An underwater mountain range where new ocean floor is formed at a divergent plate boundary.

Intrusive Igneous Rock

Rock formed from the slow cooling of magma beneath the Earth's surface

Ionic Bonding

A chemical bond where atoms gain or lose electrons

Lithification

The process that turns loose sediment into sedimentary rock

Asthenosphere

A weak

Basalt

An extrusive (volcanic) igneous rock with a fine-grained texture

Caldera

A large circular depression (over 1 km wide) formed by the collapse of a volcano after a massive

Composite Volcano

A steep volcano

Continental Crust

Light-colored

Convergent Boundary

A boundary where two tectonic plates move toward each other

Covalent Bonding

A strong type of chemical bond where atoms share electrons to fill their outer shells.

Divergent Boundary

A boundary where two tectonic plates move apart

Epicenter

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

Extrusive Igneous Rock

rock formed from the rapid cooling of lava on the Earth's surface

Fault

A fracture in rock where movement has occurred.

Focus (Hypocenter)

The point inside the Earth where a fault first breaks and energy is released during an earthquake.

Granite

An intrusive igneous rock with a coarse-grained texture and felsic composition

Igneous Rock

Rock formed from the cooling and solidification (crystallization) of magma or lava.