Questions and Answers
Scientists mapped the depth of the ocean floor using a device called a(n) ______ __________.
echo sounder
In the middle of the oceans are large mountain ranges called ____ _______ _________.
mid-ocean ridges
Existence of these mountain ranges was confirmed through echo-sounder research.
True
These underwater mountain ranges are much _______ than mountain ranges on land.
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__________ ____________ occurs when new oceanic crust forms at a mid-ocean ridge and old crust moves away from the ridge.
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What rises from the mantle through cracks in the crust?
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What erupts as lava from volcanic vents along the mid-ocean ridge?
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The molten rock cools and becomes ________, the rock that forms the oceanic crust.
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New oceanic crust forms along a mid-ocean ridge, and _______ crust moves away from the ridge.
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The topography of the sea floor includes the _______ ________ and rugged mountains.
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What pushes on the crust above it, causing it to crack and form jagged mountains?
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What erupts from the center of the ridge, cooling, and building up around the ridge?
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Eventually, sediment forms on top of the oldest oceanic crust, making a smooth seafloor called the _______ _______.
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Seafloor spreading helps explain continental drift because it shows that continents move with the oceanic crust as it spreads away from mid-ocean ridges.
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Evidence to support seafloor spreading first came from studying the ____________ of rocks on the seafloor.
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Earth's outer core causes Earth's _________________.
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The direction of Earth's magnetic field _________ often.
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Match the magnetic property or event with its description:
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Magnetic signatures form when iron-rich minerals in cooling lava align with the direction of Earth's magnetic field.
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The direction of a magnetic field in minerals can be determined by using a device called a(n) _______________.
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Magnetometers show ______________ magnetic stripes on either side of a mid-ocean ridge.
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These stripes alternate normal polarity and reversed polarity showing that each stripe was formed at the mid-ocean ridge and then moved away.
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Sediment collected from the seafloor show that sediment farther away from a mid-ocean ridge is _____ than the sediment that is closer to the ridge.
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Study Notes
Ocean Floor Mapping
- Echo sounder is a device used by scientists to map ocean floor depth.
- Large mountain ranges called mid-ocean ridges exist in the middle of oceans.
- Existence of mid-ocean ridges was confirmed through echo-sounder research.
Characteristics of Mid-Ocean Ridges
- Underwater mountain ranges are significantly longer than land-based ranges.
- Seafloor spreading is the process where new oceanic crust forms at mid-ocean ridges, pushing older crust away.
Formation of Oceanic Crust
- Magma rises from the mantle through crust cracks and erupts as lava from volcanic vents at mid-ocean ridges.
- Upon cooling, molten rock solidifies into basalt, which constitutes the oceanic crust.
Sea Floor Topography
- The seabed includes abyssal plains and rugged mountains, shaped by various geological processes.
- Magma can push on the crust, causing cracks and forming jagged seafloor mountains.
Sediment and Seafloor Features
- Lava that erupts from the center of mid-ocean ridges builds up around the ridge.
- Older oceanic crust becomes covered with sediment, forming smooth areas known as abyssal plains.
Continental Drift and Magnetic Evidence
- Seafloor spreading supports the theory of continental drift, demonstrating that continents move with oceanic crust.
- Studying the magnetism of seabed rocks provides evidence for seafloor spreading.
Earth's Magnetic Field
- Earth's outer core generates its magnetic field, which frequently reverses direction.
- Magnetic polarity is classified as normal polarity when magnets point north and reversed polarity when they point south.
Magnetic Signatures
- Iron-rich minerals in cooling lava align with Earth's magnetic field, creating magnetic signatures.
- Magnetometers detect the direction of magnetic polarity in minerals.
Magnetic Patterns and Sediment Age
- Parallel magnetic stripes appear on either side of mid-ocean ridges, alternating between normal and reversed polarity.
- Sediment from the seafloor reveals that sediment further from mid-ocean ridges is older than that closer to the ridges.
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Description
Explore fundamental concepts in oceanography with flashcards from SCIENCE Lesson 2. This quiz covers essential vocabulary related to ocean floor mapping and geological formations like mid-ocean ridges. Test your understanding of the theories developed through scientific research.
