Evidence of Plate Motions

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Continental Drift Noun

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[kon-tuh-nen-tl drift]

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Continental Drift

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The hypothesis that all continents were once fused together and have slowly moved to their current positions over time.

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Example: Arrows show how continents move over time, illustrating continental drift.

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Hypothesis Noun

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[hy-poth-uh-sis]

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Hypothesis

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An evidence-based idea that can be tested by experimentation and serves as a starting point for scientific inquiry.

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Example: Observations lead to questions and multiple hypotheses, which are tested by experiments.

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Pangaea Noun

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[pan-jee-uh]

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Pangaea

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The name given to the supercontinent that was formed by the fusion of all of today's continents long ago.

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Example: This map shows Pangaea, the supercontinent formed by all today's continents long ago.

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Fossils Noun

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[fos-uhls]

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Fossils

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The preserved traces or remains of ancient organisms found in rock, used as evidence for past life and events.

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Example: Shows how organisms become fossils over time through burial and preservation in rock layers.

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Glossopteris Noun

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[glaw-sop-tuh-ris]

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Glossopteris

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A fernlike plant fossil from 250 million years ago, found on multiple continents, providing evidence for continental drift.

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Example: The image shows a Glossopteris leaf fossil, illustrating evidence for continental drift.

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Mesosaurus Noun

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[mes-uh-sawr-us]

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Mesosaurus

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A freshwater reptile fossil found in both South America and Africa, suggesting these continents were once connected as one.

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Example: The Mesosaurus fossil shows how its presence in different continents supports the idea they were once connected.

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Oceanography Noun

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[oh-shuh-nog-ruh-fee]

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Oceanography

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The scientific study of Earth's oceans, which provided key evidence for the mechanism that drives continental drift.

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Example: The image shows how oceanic crust moves under continental crust, forming a trench, which is evidence of plate motion.

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Plates Noun

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[playts]

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Plates

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The large, rigid, moving pieces of the lithosphere that make up the solid outer surface of the Earth.

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Example: Tectonic plates move and interact, causing geological features like mountains.

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Mid-ocean ridge Noun

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[mid-oh-shuhn rij]

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Mid-ocean ridge

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A long, zipper-like chain of undersea mountains where new ocean floor is formed by volcanic activity.

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Example: The image shows a mid-ocean ridge where magma rises to form new ocean floor, illustrating plate motions.

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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 creates new oceanic crust at a mid-ocean ridge, pushing older rock away.

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Example: Magma rises at a mid-ocean ridge, creating new oceanic crust and pushing older crust away.