Podcast
Questions and Answers
What percent of the Earth's surface do oceans cover?
What percent of the Earth's surface do oceans cover?
Which ocean basin is the largest and deepest?
Which ocean basin is the largest and deepest?
What is the name of the single supercontinent that existed 180 million years ago?
What is the name of the single supercontinent that existed 180 million years ago?
Alfred Wegener proposed the hypothesis of continental drift in 1912.
Alfred Wegener proposed the hypothesis of continental drift in 1912.
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Which of the following is NOT evidence supporting continental drift?
Which of the following is NOT evidence supporting continental drift?
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What type of plate boundary creates new oceanic crust?
What type of plate boundary creates new oceanic crust?
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Which of the following is an example of a convergent plate boundary?
Which of the following is an example of a convergent plate boundary?
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What type of plate boundary is responsible for the formation of the Himalayas?
What type of plate boundary is responsible for the formation of the Himalayas?
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What is the name of the layer where salinity changes rapidly in the ocean?
What is the name of the layer where salinity changes rapidly in the ocean?
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What is the layer called where temperature changes rapidly in the ocean?
What is the layer called where temperature changes rapidly in the ocean?
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Which of the following dissolved gases is essential for photosynthesis?
Which of the following dissolved gases is essential for photosynthesis?
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Which of the following is NOT a source of carbon dioxide in the ocean?
Which of the following is NOT a source of carbon dioxide in the ocean?
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Which process converts free nitrogen into a usable form for organisms?
Which process converts free nitrogen into a usable form for organisms?
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Seawater transparency is directly proportional to turbidity.
Seawater transparency is directly proportional to turbidity.
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Blue light penetrates deeper in the ocean than red light.
Blue light penetrates deeper in the ocean than red light.
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How does pressure change with depth in the ocean?
How does pressure change with depth in the ocean?
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Which of the following is NOT a type of ocean wave?
Which of the following is NOT a type of ocean wave?
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Tides are primarily influenced by the gravitational pull of the sun.
Tides are primarily influenced by the gravitational pull of the sun.
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Which type of tide occurs when the sun, moon, and Earth are aligned in a straight line?
Which type of tide occurs when the sun, moon, and Earth are aligned in a straight line?
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Which of the following is NOT a type of vertical water movement?
Which of the following is NOT a type of vertical water movement?
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The Coriolis effect causes water to spiral in the direction of the wind.
The Coriolis effect causes water to spiral in the direction of the wind.
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Ocean currents are solely affected by Earth's rotation.
Ocean currents are solely affected by Earth's rotation.
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Study Notes
Marine Geology, Chemistry, Physics
- Oceans cover approximately 71% of Earth's surface.
- The Northern Hemisphere is 61% ocean, while the Southern Hemisphere is 80% ocean.
- Ocean basins are categorized as Pacific (largest and deepest), Atlantic (roughly equal), Indian (roughly equal), and Arctic (smallest and shallowest).
Structure of the Earth
- Density decreases from the center outward.
- The crust (both oceanic and continental) is akin to ice chunks floating on water (mantle).
- All life on Earth is influenced by the mantle's movement.
Oceanic and Continental Crust
- Oceanic crust has a density of 3.0 g/cm³.
- Oceanic crust is young and dark, primarily composed of basalt rich in iron and magnesium.
- Continental crust has a density of 2.7 g/cm³.
- Continental crust is old and light, mainly composed of granite with sodium, potassium, and quartz.
Plate Tectonics
- Sir Francis Bacon suggested that continents were once one large supercontinent.
- Alfred Wegener proposed continental drift in 1912.
- Pangea was a single supercontinent that existed 180 million years ago.
- Wegener questioned continental connections and the forces causing separation.
- Evidence for continental drift includes continental margin configuration matching (75%), matching rocks and fossils across the Atlantic, rock magnetism, and ocean bedrock age (nothing older than 175 million years; oldest land rocks 3.9 billion years).
Plate Boundaries
- Divergent: Plates move apart, creating new oceanic crust (Mid-Atlantic Ridge).
- Convergent: Plates collide, resulting in trenches and potentially volcanic arcs (Mariana Trench, Japan, Andes).
- Compression: Continental plates collide creating mountain ranges (Himalayas).
- Lateral (Transform): Plates slide past each other (San Andreas Fault).
Marine Sediments
- Particle size indicates origin and transport method.
- Shape reflects different transport distances.
- Color reflects composition (white - calcium carbonate, black - high organic matter, red - iron oxide, gray - high silica).
- Pelagic sediments come from processes within the ocean.
- Biogenous sediments are composed of microscopic organisms' skeletons/shells.
- Inorganic sediments are primarily clay (70%), often carried from land by currents.
- Volcanic sediments are from volcanic activity.
- Lithogenous sediments are derived from land rock breakdown.
Properties of Water
- Water exists in three states (liquid, gas, solid).
- Water has a high boiling point (100°C).
- Viscosity of water increases as temperature decreases.
- Ice is less dense than water (allows it to float).
- Water has a high heat capacity which moderates temperature changes in coastal areas.
- Surface tension allows some organisms to "walk" on water.
- Water is a solvent, dissolving more substances than any other liquid.
Seawater Composition
- Salinity measures dissolved salts in seawater.
- Common salts include chloride, sodium, magnesium, calcium, and potassium.
- The overall salinity percentage remains relatively constant (3.5% or 35 ppt).
- Salinity ratios remain consistent, even though precipitation and evaporation can cause local variations.
- Factors affecting salinity include evaporation, rainfall, and river runoff.
Ocean Depth Profiles
- Salinity, temperature, and density change with depth.
- The halocline is the zone of rapid salinity change below the surface, stabilizing at a consistent level.
- The thermocline is the layer of rapid temperature change beneath the surface layer.
- The pycnocline is the layer where density changes rapidly below the thermocline.
Dissolved Gases
- Seawater contains oxygen (0-9%) used by organisms. Oxygen levels decrease with depth and are highly affected by wind-driven motion and turbulence.
- Carbon dioxide is essential for photosynthesis.
- Nitrogen is necessary for building amino acids and proteins; it must be converted into other usable forms for organisms.
Transparency
- Seawater is relatively transparent, depending on suspended particles.
- Turbidity measures cloudiness.
- Light penetrates to different depths, affecting light-dependent processes like photosynthesis.
- Different colors of light penetrate to varying depths (red -> blue).
Water Movement
- Waves are initiated by wind, affected by wind speed, fetch (contact area), and topography. Water molecules move, but do not travel with the wave.
- Plunging waves occur on steep slopes.
- Spilling waves occur on gently sloping beaches.
- Surging waves occur on vertical cliffs.
- Currents are large-scale water movements caused by wind, density, Earth's rotation, and tides.
Tides
- Tides are caused by the gravitational pull of the sun and the moon, and the Earth's rotation.
- Diurnal tides have one high and one low tide per day.
- Semi-diurnal tides have two high and two low tides per day.
- Mixed semi-diurnal tides have two high and two low tides of unequal heights per day.
Monthly Tidal Cycle
- Spring tides occur when the sun, moon, and Earth are aligned (full and new moon).
- Neap tides occur when the sun, moon, and Earth are at right angles (first and third quarter moon).
- The cycle repeats every 28 days.
Vertical Water Movements
- Sinking cold water (overturn).
- Upwelling brings nutrient-rich water to the surface.
- Downwelling moves heat and oxygen to the deep ocean.
- Coriolis Effect causes deflection of water.
- Ekman transport causes spiraling of water due to wind.
- Various surface currents exist based on wind systems, density differentials and position relative to continents. and other topographical features.
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Description
Test your knowledge on marine geology, including the composition and properties of oceanic and continental crust, as well as the fundamental concepts of plate tectonics. This quiz covers the structures that shape our Earth and how they interact with the oceans. Ideal for students studying earth sciences or marine geology.
