Plate Tectonics

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Hypothesis Noun

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[hy-poth-e-sis]

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Hypothesis

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An evidence-based idea that can be tested by experimentation or investigation, serving as a starting point for scientific inquiry.

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Example: A hypothesis suggests adding fertilizer increases plant size, tested by comparing growth with and without fertilizer.

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Continental Drift Noun

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[kon-ti-nen-tal drift]

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Continental Drift

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The hypothesis that all continents were once fused together and have slowly moved apart over time.

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Example: The image shows Pangaea, explaining how continents were once connected before drifting apart.

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Fossil Noun

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[fos-il]

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Fossil

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The preserved traces or remains of ancient organisms that are found in rock, providing evidence of past life.

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Example: This image shows a fossil, the preserved remains of an ancient organism, embedded in rock.

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Pangaea Noun

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[pan-JEE-uh]

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Pangaea

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The name of the supercontinent that existed millions of years ago when all of Earth's landmasses were fused together.

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Example: The image shows Pangaea, a supercontinent where today's continents were once joined together.

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Mid-Ocean Ridge Noun

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[mid-o-shun rij]

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Mid-Ocean Ridge

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A long, zipper-like chain of undersea mountains that runs through Earth's oceans where new oceanic crust is formed.

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Example: The image shows how magma rises at a mid-ocean ridge to form new oceanic crust.

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Sea-Floor Spreading Noun

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[see-flor spred-ing]

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Sea-Floor Spreading

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The process where molten rock flows up through a crack at a mid-ocean ridge, creating new ocean floor.

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Example: Magma rises at a mid-ocean ridge, creating new ocean floor as it cools.

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Subduction Noun

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[sub-DUK-shun]

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Subduction

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The sinking movement of a dense oceanic plate back into the mantle, which typically occurs at an ocean trench.

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Example: The image shows the oceanic crust sinking beneath the continental crust at a trench, illustrating subduction.

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Ocean Trench Noun

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[o-shun trench]

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Ocean Trench

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A deep undersea valley that marks the place where a dense oceanic plate is sinking back into the mantle.

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Example: The image shows an ocean trench where the oceanic plate sinks beneath the continental plate, forming a deep valley.

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Plate Tectonics Noun

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[playt tek-ton-iks]

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Plate Tectonics

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The scientific theory that Earth's lithosphere is broken into large plates that are in slow, constant motion.

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Example: The image shows Earth's plates moving over the mantle, explaining plate tectonics.

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Theory Noun

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[THEE-uh-ree]

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Theory

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In science, a well-substantiated explanation of some aspect of the natural world that is supported by a vast array of evidence.

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Example: The cycle shows how scientific theories are developed through observation, questioning, and experimentation.