Questions and Answers
What is bathymetry and what are the four main methods that scientists use to study bathymetry?
Bathymetry is the study of the ocean floor, including ocean depth and features. The four main methods are Multibeam Sonar, Side-scanning Sonar, Satellite Altimetry, and Seismic Profiling.
What is multibeam sonar?
Multibeam sonar utilizes multiple frequencies of sound to generate detailed images of the ocean floor.
What is side-scanning sonar?
Side-scanning sonar generates detailed images of the ocean floor by towing a sonar instrument behind a survey ship.
What is satellite altimetry?
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What is seismic profiling?
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What does the hypsographic curve illustrate about Earth's surface?
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What are the average and maximum depths of the ocean?
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What are continental margins?
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What are passive continental margins?
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What are active continental margins?
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Match the following continental margin features:
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What are submarine canyons?
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What are deep-sea fans?
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What are turbidity currents?
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What is graded bedding, and how does it form?
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Why are the abyssal plains so flat?
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Why are a majority of the world's trenches found in the Pacific Ocean basin?
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Study Notes
Ocean Bathymetry
- Bathymetry studies the ocean floor, examining depth and features analogous to terrestrial topographic maps.
- Key methods for studying bathymetry:
- Multibeam Sonar: Uses multiple sound frequencies to create detailed images of the ocean floor over a wide strip (up to 60 km).
- Side-Scanning Sonar: Towed behind a ship, it maps ocean floors in swaths, filling in gaps directly beneath the instrument.
- Satellite Altimetry: Measures ocean surface elevation variations due to gravitational attraction, reflecting the seafloor’s shape.
- Seismic Profiling: Employs sound frequencies to analyze sub-surface materials and seafloor layers.
Hypsographic Curve
- Combines bathymetric and topographic data to depict relationships between Earth's land heights and ocean depths.
Ocean Depths
- Average ocean depth ranges between 3,000 and 6,000 meters (3 to 6 kilometers).
- The Mariana Trench is the deepest point, measuring 11,022 meters (11 kilometers).
Continental Margins
- Continental margins transition from continental crust (granite) to oceanic crust (basalt).
- Classified as active (associated with a plate boundary) or passive (not associated with a plate boundary).
Continental Margin Features
- Key features include:
- Continental shelf
- Shelf break
- Continental slope
- Continental rise
Submarine Canyons
- Submarine canyons, cutting into the continental shelf, are formed by turbidity currents, which are underwater landslides of sediment.
Deep-Sea Fans
- Created at the base of continental slopes by turbidity currents, deep-sea fans comprise graded bedding layers and contribute to the continental rise.
Turbidity Currents
- Fast-moving underwater currents that flow downslope due to the weight of carried sediments.
Graded Bedding
- Layers formed from turbidite deposits created by turbidity currents.
Abyssal Plains
- Very flat seabed formed by slow deposition of fine sediments over time, which fills in depressions and irregularities.
Oceanic Trenches
- Majority located in the Pacific Ocean basin, linked to the tectonic activity conducive to their formation.
- Pacific Ring of Fire: Volcanic region encircling the Pacific Ocean, notable for frequent earthquakes and volcanic eruptions.
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Description
Explore the fascinating world of ocean bathymetry, focusing on methods like multibeam sonar, side-scanning sonar, and satellite altimetry. Learn how these techniques help map the ocean floor and understand its features. Delve into the significance of the hypsographic curve and the average depths of oceans.