Geology Quiz - Active Earth

Who is the father of continental drift?

Alfred Wegner

What is Paleomagnetism?

Once the rock forms, those crystals are locked into place, revealing the magnetic signature at its time of formation

What is it called when the magnetic poles flip?

Magnetic reversal

What are Mid-ocean ridges?

large and long connected underwater mountain chains

What are ocean trenches?

incredibly deep areas on the ocean floor (up to 11 km deep)

What is Magnetic striping?

The magnetic signatures of the mid-ocean ridges

Identical patterns of normal and reversed paleomagnetism were found on either side of mid-ocean ridges

What is Seafloor spreading?

Hess believed that the ocean ridges were areas where new ocean floor was being made

What is subduction?

The process in which the seafloor spread out from the mid-ocean ridge and eventually recycled back into the Earth at the deep ocean trenches

What are Plate Tectonics?

pieces of the Earth’s lithosphere (called plates) move in relation to each other

What are Plates?

The Earth’s lithosphere (crust and uppermost mantle) is divided into Plates

Plates are rigid and deform by breaking to produce earthquakes

What are Passive Margins?

found at the edge of continents where the continent and the surrounding oceanic crust are on the same tectonic plate

What are Active Margins?

where the edge of a continent coincides with a plate boundary, and earthquake and volcanic activity is common

What is a Divergent Boundary?

Is found between two plates that move in opposite directions from each other

What is a Convergent Boundary?

are when two plates collide

What are the three types of Convergent Boundaries?

Continental-continental

Continental-oceanic

Oceanic-oceanic

Continental-Oceanic Convergence

Ocean crust is denser than continental crust, so the oceanic crust is forced down into the mantle

Leads to continental arc volcanoes

Oceanic-Oceanic Convergence

When two oceanic crusts collide, whichever plate is slightly colder and denser will subduct

Leads to island arc volcanoes

Continental- Continental Convergence

When two continental crusts collide, neither of the plates can subduct into the mantle, since both are made up of low-density granitic rock

What are Transform Boundaries?

where two plates move alongside and past each other, rather than directly towards or away form each other – move past each other

What is a Hot Spot?

is a plume of magma originating in the lower mantle and rising upward into or through the crust

What are the three main types of forces rocks experience on Earth

• Compressional

  • Pushing in on it

• Tensional

  • Pulling it

• Shear Forces

  • One side is going one way, one side is going the other

What is the difference between a Fold and a Fault?

Folds - rocks bend under pressure

Faults - rocks break under pressure

What is the Law of Original Horizontality?

Layers are usually laid down flat

What are the 2 types of large-scale folds?

• Dome

• Basins

What are the 3 types of Faults?

o   Dip-slip faults – vertical movement

o   Strike-slip faults – horizontal movement

o   Oblique-slip vaults – combination of dip-slip and strike-slip – diagonal

What is a hanging wall & a footwall?

The two sides of the fault

The hanging wall goes down relative to the footwall

What is a Normal Fault?

the hanging wall appears to have moved down relative to the footwall

What is a Reverse Fault?

the hanging wall appears to have moved up relative to the footwall

What is a Thrust Fault?

a reverse fault with a very shallow angle (< 10 degrees)

What are seismic waves?

When the earthquake happens, seismic waves propagate out from the focus of the earthquake

What is the difference between Body Waves and Surface Waves?

• Wave energy from an earthquake can travel into the Earth via body waves or along the Earth’s surface via surface waves

• Body waves travel faster than surface waves

What are the 2 types of Body Waves?

• Primary waves (P waves)

• Secondary waves (S waves)

What are Primary waves?

• Compressional waves causing the rock to expand and contract as they travel

• These are the fastest waves from an earthquake and they can travel through any medium

What are Secondary waves?

• Transverse waves

• These can only travel through solids and are the second fastest earthquake waves

  • P waves go through the center of the Earth, but S waves do not

What are the 2 types of Surface waves?

• Love waves

• Rayleigh waves

What are Love waves?

cause the surface rocks to move back and forth and to have a lateral motion with respect to how the wave is propagated

What are Rayleigh waves?

cause a rolling motion within the Earth, causing the surface to move up and down like ocean waves

What is a seismometer & a seismograph?

Seismometer is an instrument that can be used to detect an earthquake

A Seismograph are used to both detect and record earthquakes

What replaced the Richter scale to measure the power of earthquakes?

The Moment magnitude scale