Midterm 1 Review Questions: Origin of Earth & Oceans and Marine Geology

These flashcards cover key concepts from the midterm review on the origin of Earth and oceans, marine geology, plate tectonics, marine sediments, and related processes.

What is the big bang hypothesis/theory?

A scientific explanation that the universe originated from a singularity and has been expanding ever since.

What is nuclear fusion?

A process in which two light atomic nuclei combine to form a heavier nucleus, releasing energy.

Which is the most abundant element in the universe?

Hydrogen.

How are the heaviest elements formed? What is a supernova?

Heaviest elements are formed in stars during their life cycle and particularly during a supernova, which is a massive explosion resulting from a star's death.

What is the process that forms planets out of small particles?

Accretion.

How old is the universe? Solar system? Earth?

The universe is approximately 13.8 billion years old, the solar system is about 4.6 billion years old, and Earth is about 4.5 billion years old.

How was the moon formed?

The moon was formed from debris ejected into orbit around Earth after a Mars-sized body collided with Earth.

Define density. How did Earth become density stratified?

Density is mass per unit volume. Earth became density stratified due to the differentiation of materials during its formation, where heavier elements sank towards the core.

Where did the Earth’s current atmosphere and oceans come from? Is the Earth’s current atmosphere similar or different from its first atmosphere?

The current atmosphere and oceans originated from volcanic outgassing and possibly cometary impacts; they are different from the first atmosphere, which was primarily composed of hydrogen and helium.

What is the oxygen revolution?

The period during which oxygen levels in Earth's atmosphere increased dramatically due to photosynthetic activity, primarily from cyanobacteria.

What are the most abundant gases in the Earth’s current atmosphere?

Nitrogen and oxygen.

What % of the Earth’s surface is covered by water?

Approximately 71%.

Which hemisphere of the Earth contains the greater proportion of ocean surface?

The Southern Hemisphere.

Which one is larger – the average depth of the ocean or the average land elevation?

The average depth of the ocean is larger.

Which is the Earth’s tallest/highest mountain? Where is the Earth’s highest elevation?

Mount Everest is the tallest mountain, located in the Himalayas.

Where is the Ocean’s deepest part?

The Mariana Trench.

What is echo sounding used for? What is meant by the equation: D = V (T/2)?

Echo sounding is used to measure water depth; D is the depth, V is the speed of sound in water, and T is the time taken for the echo to return.

What is a contour line? Bathymetry?

A contour line represents areas of equal depth on a map; bathymetry is the study of underwater depth of ocean floors.

What is the principle of satellite altimetry?

Satellite altimetry measures the time it takes for a radar signal to bounce back from the Earth's surface to gauge the ocean's surface height.

What does seismology tell us about the interior of the Earth?

Seismology uses seismic waves to infer the composition and structure of Earth's interior.

Compare and contrast P and S seismic waves.

P waves are compressional and can travel through solids and liquids, while S waves are shear waves that can only travel through solids.

How does seismology tell us that the outer core is liquid?

S waves do not travel through the outer core, indicating it is liquid, as they are only able to pass through solid materials.

Besides seismic and gravimetric constraints, what are the other sources of information on the Earth’s structure and composition?

Other sources include geological samples, meteorites, and studies of Earth's magnetic field.

Describe the major internal layers of the Earth. (Make sure you know the major constituents of each layer!)

The layers include the crust (silicates), mantle (silicate minerals), outer core (liquid iron and nickel), and inner core (solid iron and nickel).

Among the Earth’s internal layers, which one is the densest? The lightest?

The inner core is the densest, while the crust is the lightest.

What is a granite? How does it differ from a basalt?

Granite is a coarse-grained igneous rock rich in silica; basalt is a fine-grained igneous rock that is lower in silica.

What is the most abundant material on or in the Earth?

Silicate minerals.

What is the continental drift hypothesis? Give some evidence.

The hypothesis that continents have moved over geological time; evidence includes the fit of continental coastlines and fossil similarities across continents.

What is the principle of uniformitarianism? Catastrophism?

Uniformitarianism is the concept that geological processes are uniform over time, while catastrophism suggests that Earth's features are the result of sudden, short-lived events.

What are lithospheric/tectonic plates?

Lithospheric plates are large sections of Earth's crust that move and interact at their boundaries.

Where are most of the Earth’s seismic activities located?

Most seismic activities are located along tectonic plate boundaries.

Where and how is the oceanic crust formed?

Oceanic crust is formed at mid-ocean ridges through volcanic activity as magma rises to the surface.

What are mid ocean ridge basalts (MORB); how and where are they formed?

MORB are basalts formed at mid-ocean ridges from the melting of mantle material as tectonic plates diverge.

What are magnetic stripes; explain how they are formed?

Magnetic stripes are patterns of magnetic anomalies on the ocean floor formed by the periodic reversal of Earth's magnetic field during seafloor spreading.

What is the seafloor spreading hypothesis?

The hypothesis that new oceanic crust is formed at mid-ocean ridges and gradually moves away from the ridge.

Which is older, the oceanic crust or continental crust? Where can you find the Earth’s oldest rocks? How old is the Earth’s oldest rock?

Continental crust is older; Earth's oldest rocks can be found in the Canadian Shield, with some dated at around 4 billion years.

What is Pangaea?

A supercontinent that existed during the late Paleozoic and early Mesozoic eras, consisting of all Earth's landmasses.

The Hawaiian island chain is generally classified as what type of volcanism?

Hotspot volcanism, where a plume of hot mantle material creates volcanoes as tectonic plates move over it.

Explain this type of volcanism. Can this type of volcanism occur in continental areas?

Hotspot volcanism occurs due to a stationary hot spot beneath moving plates and can occur in continental areas, as seen with the Yellowstone hotspot.

What are the differences and similarities among continental drift hypothesis, seafloor spreading hypothesis, hotspot hypothesis, and plate tectonics theory?

All propose mechanisms for the movement of Earth's crust; continental drift focuses on landmass movement, seafloor spreading on ocean floor production, and hotspot on stationary mantle plumes under plates.

What is isostatic equilibrium? Or What does it tell us about Earth’s surface elevation?

Isostatic equilibrium is the state in which the Earth's crust floats on the denser mantle; it explains variations in crustal elevation.

What are the major sources of the Earth’s heat?

Major sources include the decay of radioactive isotopes and residual heat from the planet's formation.

How does heat move from the interior to the surface of Earth?

Heat moves through conduction, convection, and advection.

What is a divergent plate boundary?

A boundary where two tectonic plates move away from each other, typically leading to seafloor spreading.

What is a convergent plate boundary and what are the major types of convergent plate boundaries?

A convergent boundary is formed when tectonic plates collide; types include ocean-ocean, ocean-continent, and continent-continent.

What are subduction zones? Why are they deep?

Subduction zones are areas where one tectonic plate is forced beneath another; they are deep due to the downward movement of the oceanic plate.

When two oceanic plates converge, which one would subduct?

The older, denser oceanic plate would subduct.

Contrast passive and active continental margins.

Passive margins are tectonically inactive and typically have wide continental shelves, while active margins are tectonically active with narrow shelves and steep slopes.

What is the 'Pacific Ring of Fire'?

A horseshoe-shaped area in the Pacific Ocean basin known for high volcanic and seismic activity.

How were the Himalayas formed?

The Himalayas were formed by the collision of the Indian and Eurasian tectonic plates.

What is a transform plate boundary?

A boundary where two tectonic plates slide past each other horizontally.

What type of plate boundary is the San Andreas fault system?

The San Andreas fault is a transform plate boundary.

What are the two types of continental margins? How are they formed?

The two types are passive margins, formed by continental rifting and subsequent sediment accumulation, and active margins, formed by tectonic activity.

Describe the different components of continental margins – make sure that you understand each component well.

Components include the continental shelf, slope, and rise.

What is the main cause of the rise and fall of sea level during the last 250,000 years and why?

The main cause is glacial-interglacial cycles due to climate changes affecting ice volumes.

How low was the sea level at the climax of the last ice age some 18,000 years ago? How high was the sea level during the last interglacial period about 120,000 years ago?

Sea level was approximately 120 meters lower during the last ice age and about 6-9 meters higher during the last interglacial period.

What are submarine canyons and how do they form?

Submarine canyons are steep-sided valleys cut into the seabed; they form primarily through erosion by underwater currents.

What are the main differences between the western and eastern U.S. continental margins?

The western U.S. margin is active, characterized by tectonic activity and narrow shelves, while the eastern margin is passive with wide continental shelves.

Describe the different components of the deep ocean basin.

Components include continental slopes, abyssal plains, mid-ocean ridges, and oceanic trenches.

Why are mid-ocean ridges shallower than adjacent seafloor?

Mid-ocean ridges are shallower because they are composed of younger, hotter, less dense material.

What is the main difference between a Pacific (fast-spreading) and Atlantic or Indian (slow-spreading) mid-ocean ridge?

Pacific ridges have steeper slopes and faster rates of spreading than Atlantic or Indian ridges.

Contrast mid-ocean ridge style of volcanism with subduction zone volcanism (i.e., how are their respective magmas/lavas formed?).

Mid-ocean ridge volcanism results from decompression melting of mantle material, while subduction zone volcanism occurs from melting of subducted materials and fluids.

What are seamounts and how are these formed?

Seamounts are underwater mountains formed from volcanic activity, rising from the ocean floor.

What are black smokers and how are these formed?

Black smokers are hydrothermal vents that emit dark, mineral-rich water created by sea water interacting with magma.

Make sure that you can identify some of the major tectonic and bathymetric features on the Earth’s surface in a map.

Tectonic features include mountains and trenches; bathymetric features include ridges and abyssal plains.

Describe the 3 major rock types.

Igneous, sedimentary, and metamorphic rocks.

Which is the most abundant rock type a) in the crust and why? b) on the surface and why?

a) Igneous rocks in the crust due to volcanic activity; b) sedimentary rocks on the surface due to erosion and deposition.

What are the two major types of sediments?

Terrigenous and biogenic sediments.

What are the different processes in the sedimentary rock cycle; for example, what is diagenesis?

Processes include weathering, erosion, transportation, deposition, and lithification; diagenesis involves the chemical, physical, and biological changes occurring after sediment is deposited.

The ocean is over 4 b.y old, and yet, modern marine sediments are rarely older than ~180 m.y. Why?

Most marine sediments are recycled through the rock cycle and are continuously being formed and deposited.

Remember the 'relative' sizes of sedimentary particles, examples of each particle, how these particles generally behave during sediment transport, where they are deposited in the oceanic environment, and rock types derived from each particle size.

Sizes vary from clay (smallest), silt, sand, to gravel (largest); smaller particles are transported further and deposited in quieter waters, while larger particles settle quickly.

What are the main types of marine sediments according to source, and type examples of each class?

Types include lithogenous (derived from rocks), biogenous (from organisms), and hydrogenous (from chemical precipitation).

How are terrigenous sediments transported into the ocean basin?

Terrigenous sediments are transported by rivers, wind, and glacial activity.

Which type of sediment is most widely distributed in the ocean basin?

Lithogenous sediments.

How do neritic sediments differ from pelagic ones?

Neritic sediments are found in shallow water near coastlines, while pelagic sediments are found in deep ocean areas.

What are sedimentary oozes; major types of sedimentary oozes?

Sedimentary oozes are sediments that accumulate on the seafloor; major types include calcareous oozes (from calcium carbonate organisms) and siliceous oozes (from silica-based organisms).

The rock cycle includes mechanical and chemical weathering – how does each impact the ocean?

Mechanical weathering breaks down rocks without chemical changes, while chemical weathering alters minerals and releases nutrients into the ocean.

What is clastic versus non-clastic material?

Clastic materials are formed from fragments of other rocks, while non-clastic materials are formed from chemical precipitation or biological processes.

Give common examples of organisms that form oozes.

For example, foraminifera and coccolithophores for calcareous ooze, and diatoms for siliceous ooze.

Why is carbonate sediment rare in the deepest parts of the ocean?

Carbonate sediments dissolve in deeper, colder waters due to higher pressure and lower pH.

What are examples of hydrogenous sediment? Evaporites?

Hydrogenous sediments include manganese nodules; evaporites are formed from the evaporation of seawater, like halite and gypsum.

How are evaporites formed?

Evaporites are formed through the evaporation of water that leaves behind mineral deposits.