Geology 101- Final Exam

What is Geology?

The study of the Earth.

What do Geologists study?

1. Rock.

2. Magma.

3. Sediments.

What are landscapes?

The overall shape and character of the land surface in a region.

What is bedrock?

Rock still attached to the earth’s crust.

What is an outcrop?

An exposure of Bedrock.

What is a hand sample?

A piece of rock, about the size of a fist, that can be collected for study.

What is a drilled core?

Round drilled cutting of rock below the earth’s surface.

What is a thin section?

A 3/100 mm thick slice of rock that can be examined with a petrographic microscope.

What is a model?

A representation of the construction or appearance of something.

What is a cross section?

A view formed by a plane cutting through an object to reveal a profile (a vertical section of the Earth’s crust showing the different horizons or layers).

What should you include in your cross section?

1. Elevation.

2. Layers.

3. Clues.

What is density?

A measurement of how tightly matter is crammed together (mass/volume).

What is pressure?

Continuous physical force exerted on or against an object by something in contact with it.

What is the atmosphere?

A layer of gas that surrounds a planet.

What is the atmosphere made primarily of?

Made primarily of Nitrogen & Oxygen.

What are some distinctive features of the atmosphere?

1. 200 km bottom to “space.”

2. 184 to 3600 degrees F.

3. Density ~ 0.001 gm/cc.

What is the hydrosphere?

The earth’s water, including surface water, groundwater, and liquid water in the atmosphere.

What is the hydrosphere made of?

Made of hydrogen and oxygen.

What are some distinctive features of the hydrosphere?

1. 0-11 km bottom to top edge.

2. Liquid 28-80 F.

3. Density ~ 2.8 gm/cc.

What is the crust?

The rock that makes up the outermost layer of the Earth.

What is the crust made of?

Made of Silica and Oxygen minerals.

What are some distinctive features of the crust?

1. 8-65 km bottom to top edge.

2. Air temp to 1,600 F.

3. Density ~ 2.8 grams.

What are some distinctive features of the Ocean Crust?

1. Thickness: 8-15 km.

2. Basaltic.

3. ~ 50% silica (SiO2).

4. Density: 2.9 gm/cc.

5. Age: <200 million yrs.

What are some distinctive features of the Continental Crust?

1. Thickness: 30-65 km.

2. Granitic.

3. ~ 70% silica (SiO2).

4. Density: 2.7 gm/cc.

5. Age: <4.2 billion yrs.

What is the mantle?

The thick layer of rock below the Earth’s crust and above the core.

What is the mantle made of?

Made of Magnesium, Silica, and Oxygen minerals.

What are some distinctive features of the mantle?

1. ~ 2900 km bottom to top edge.

2. 1,600 F to 4,000 F.

3. Density: ~ 3.1 ~ 4.5 gm/cc.

What is the lithosphere-asthenosphere boundary (LAB)?

The boundary between the rigid part of the mantle and the ductile portion.

What is the lithosphere?

Cooler, rigid (solid) part of crust plus upper mantle.

What does the lithosphere have a density of?

Density of 3.1 - 3.4 gm/cc.

What is the asthenosphere?

Part of the upper mantle that is warmer - near the melting point of minerals - soft and weak.

What is the core made of?

Made of iron & nickel.

What are some distinctive features of the Earth’s core?

1. Heat is produced from radioactive materials.

2. ~ 3500 km center to top edge.

3. Density ~ 11 gm/cc.

4. Has a liquid outer core and solid inner core.

What is the scientific method?

The systematic study of the structure and behavior of the physical and natural world through observation, experimentation, and the testing of theories against the evidence obtained.

What is a scientific theory?

A well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses, and facts.

What is a scientific law?

A statement that describes an observable occurrence in nature that appears to always be true.

What is the Continental Drift Theory?

The theory that the continents had all broken away from a united supercontinent he called Pangea.

What is the continental shelf?

The area between the shoreline and continental slope where the seafloor slopes gently seaward.

What are striations?

Parallel scratches, grooves, or lines on a rock’s surface, formed by friction from rocks and debris embedded in moving glaciers, fault movements (slickensides), or as natural growth patterns on mineral crystals like quartz and pyrite.

What is a cynognathus?

Triassic land reptile three meters long.

What is a lystrosaurus?

Triassic land reptile.

What is a mesosaurus?

Freshwater reptile.

Why did scientists find Wegener’s theory of continental drift so hard to accept?

1. No mechanism - implausible.

2. Little data - and not well known either (it didn’t fit the evidence as known at the time.)

3. Alternate theories - account for some of the observations.

4. A meteorologist?

5. Prevailing beliefs.

What is the Earth’s giant magnetic field?

The Earth has a giant magnetic field extending outwards from our planet’s interior that extends out into space.

It flips.

It moves.

Powered by the core’s convective energy.

What does the angle of Magnetite depend on?

The angle of Magnetite depends on its latitude relative to magnetic north when rock forms.

What is a inclination?

Angle from horizontal to the magnetic force lines.

What is PaleoMagnetism?

The study of a historic record of magnetism in rocks.

What did Dr. Stanley Keith Runcorn’s research 1960’s indicate?

1. Rocks and sediments showed magnetic north at different locations.

2. Apparent Wandering Paths for Eurasia first then North America.

3. If continental drift was accounted for the paths aligned.

What did Dr. Marie Thorp create in the late 1950’s - early 1960’s?

Dr. Marie Thorp created the first map of the sea floor in the late 1950’s - early 1960’s.

What was Harry Hess given credit for in 1962, and what did he describe with it?

Harry Hess was given credit for the theory of “Sea Floor Spreading” based on his publication in 1962. He described how a new ocean floor was created at mid-ocean ridges and was recycled by the continents.

What is Seafloor Spreading?

The process occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.

What is plate tectonics?

Plate tectonics is the scientific theory describing the large-scale motion of Earth’s lithosphere.

What is topography?

The arrangement of the natural and artificial physical features of an area.

What is a tectonic plate?

An individual piece of lithosphere that moves over the asthenosphere.

How many tectonic plates are there?

12-20 distinct plates (depending on how you count them).

What are tectonic plates typically more of compared to the continents?

Plates are typically wider than the continents.

What is an example of a large tectonic plate?

Pacific Plate.

What is an example of a small tectonic plate?

Juan de Fuca Plate.

What are the types of Plate Boundaries?

1. Divergent Boundaries- Birth of new plates. (Upwarping to Ocean).

2. Convergent Boundaries- Death of plates. (Ocean to Ocean, Ocean to Continental, Continental to Continental).

3. Transform Boundaries.

4. Hot Spots (intraplate).

What are Divergent Plate Boundaries?

The boundary between two plates that are moving apart.

What happens during a Divergent Plate Boundary?

Plates move apart & new crust forms.

In the Divergent Plate Boundaries what is the Mid-Ocean Ridge?

A submarine mountain belt that forms along a divergent oceanic plate boundary.

In Divergent Plate Boundaries what happens as the plates move apart?

As plates move apart seafloor spreading occurs.

In the Divergent Plate Boundaries what are the steps for the birth of an ocean?

1. Central Rift/Upwarping.

2. Rift Valley.

3. Linear Sea.

4. Ocean.

In the Divergent Plate Boundaries steps for the birth of an ocean what is the central rift and what is upwarping?

Central Rift: locations where the continental lithosphere stretches horizontally and thins vertically.

Upwarping: to uplift differentially to produce a broad low arching of the surface.

In the Divergent Plate Boundaries steps for the birth of an ocean what is the rift valley?

A lowland region that forms where Earth’s tectonic plates move apart, or rift.

In the Divergent Plate Boundaries steps for the birth of an ocean what is the linear sea?

A sea that forms a line due to tectonic plates moving apart.

In Divergent Plate Boundaries what creates the Red Sea, so high evaporation of sea water creates super saline conditions?

Seafloor spreading/Rifting creates the Red Sea, so high evaporation of sea water creates super saline conditions.

In Divergent Plate Boundaries what are the hazards?

1. Active volcanism and dike injection are common in both continental and ocean rifts.

2. Tensional forces cause shallow earthquakes.

What are Transform Plate Boundaries?

A boundary where one lithosphere plate slips laterally past another.

What happens during a Transform Plate Boundary?

Plates move past each other (horizontally).

What are some other names for Transform Plate Boundaries?

1. Offset Divergent boundaries.

2. Connect boundaries.

In Transform Plate Boundaries how do they show up on the sea floor?

Shows up as large fracture zones and transform fault zones on the sea floor.

In Transform Plate Boundaries what are hazards?

Result in Shallow (big) Earthquakes.

What are Convergent Plate Boundaries?

The boundary between two plates that are moving toward each other.

What happens during a Convergent Plate Boundary?

Plates move toward each other.

In Convergent Plate Boundaries what is subduction?

The process by which one oceanic plate bends and sinks into the asthenosphere beneath another plate.

In Convergent Plate Boundaries what is a trench?

A deep, elongated trough bordering a volcanic arc; a trench defines the trace of a convergent plate boundary.

In Convergent Plate Boundaries what is the subduction zone?

A long narrow zone where subduction occurs.

In Convergent Plate Boundaries where does the lower plate move into and sink through?

Lower plate moves into the asthenosphere and sinks through the mantle.

What are the types of Convergent Plate Boundaries?

1. Ocean - Ocean (O-O).

2. Ocean - Continental (O-C).

3. Continental - Continental (C-C).

What type of magma is in the Ocean - Ocean Convergent Plate Boundary?

Felsic.

What type of magma is in the Ocean - Continental Convergent Plate Boundary?

Felsic.

What happens during an Ocean - Ocean Convergent Plate Boundary?

Older, higher-density ocean plates subduct under less dense, younger ocean plates. Builds submarine trenches.

In a Ocean - Ocean Convergent Plate Boundary what is an island arc?

A chain of volcanoes that form above the non-subducting plate.

What happens during an Ocean - Continental Convergent Plate Boundary?

The higher-density ocean plates will subduct under less dense continental plates. Builds mountain ranges on the continents and trenches in the ocean.

In an Ocean - Continental Convergent Plate Boundary what are hazards?

1. Compressional force leads to megathrust (big) to deep Earthquakes, descending plate.

2. Active stratovolcanoes.

What happens during a Continental - Continental Convergent Plate Boundary?

Neither plate sinks into the asthenosphere.

What are the steps for the Continental - Continental Convergent Plate Boundaries?

1. Starts as an ocean-continental boundary until the oceanic lithosphere completely subducts.

2. Then two continental plates collide.

3. Neither plate subducts into the asthenosphere.

4. Oceanic plate detaches and sinks.

5. Compression causes a mountain range to rise.

In Continental - Continental Convergent Plate Boundaries what are hot spots?

A large plume of hot mantle material rising from deep within the Earth.

What happens during a Hot Spot Plate Boundary

Plumes of magma rise from deeper in mantle. These plumes stay fixed in place as plates move slowly over the top of them.

Where can the Hot Spots Plate Boundaries be located?

Can be located on Ocean or Continental plates or at plate boundaries.

In a Hot Spot Plate Boundary what is an ocean plate?

The dense, basalt-rich tectonic plate making up the seafloor that is slowly moving over a stationary plume of hot magma.

In a Hot Spot Plat Boundary what is an island chain?

A line in the middle of a plate starting with a volcanic island followed by extinct volcanoes.

In a Hot Spot Plate Boundary what is a continental plate?

Form a chain of calderas lead by volcanic activity.

In a Hot Spot Plate Boundary what are the hazards?

1. Earthquakes due to the movement of magma.

2. O- Active Slow flowing volcanoes.

3. C- Large very explosive volcanoes.

What is a rock?

A coherent, naturally occurring solid, consisting of an aggregate of minerals or, a mass of glass.

Coherent.

Naturally occurring.

An aggregate of one or more minerals.

What is a mineral?

Elements or compounds that are natural, crystalline, solids that form through geological processes.

What is a natural mineral produced by?

Produced by nature.

What are some distinctive features of a solid mineral?

1. Rigid.

2. Fixed shape.

3. Fixed volume.