Plate Tectonics: Evidence the Continents Moved
Aligned to MS-ESS2-3 — Next Generation Science Standards.
What this lesson teaches
Earth's outer shell is broken into slabs called tectonic plates that slowly drift on the hot, soft rock beneath. Several independent clues — coastlines that fit like puzzle pieces, matching fossils on opposite continents, and mirror-image rock patterns on the seafloor — together show the continents were once joined and have moved apart.
Worked example
The east coast of South America nests neatly into the west coast of Africa, and the same fossil reptile, Mesosaurus, is found on both. Because this small freshwater animal could never have swum across an ocean, the simplest explanation is that the two continents were once a single landmass.
Practice questions
- Cut out the continents from a world map and try to fit them together like a jigsaw puzzle.
- List three separate pieces of evidence for plate motion and explain what each one shows.
- Explain why matching mountain ranges on two different continents supports the idea that they were once connected.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Tectónica de placas: pruebas de que los continentes se movieron
La capa externa de la Tierra está fragmentada en losas llamadas placas tectónicas que se desplazan lentamente sobre la roca caliente y blanda de abajo. Varias pistas independientes —costas que encajan como piezas de rompecabezas, fósiles coincidentes en continentes opuestos y patrones de roca en espejo en el fondo marino— muestran en conjunto que los continentes estuvieron unidos y se separaron.
Ejemplo: La costa este de Sudamérica encaja bien en la costa oeste de África, y el mismo reptil fósil, Mesosaurus, se encuentra en ambas. Como este pequeño animal de agua dulce nunca pudo haber cruzado un océano nadando, la explicación más simple es que los dos continentes fueron alguna vez una sola masa de tierra.
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