• Evidence
  • Data
  • Fossils
  • Rock
  • Continent
  • Continental shelf
  • Geologic past
  • Pangea
  • Ridges
  • Volcanic ridges
  • Trenches
  • Theory of Continental Drift
  • Theory of Plate Tectonics
  • Crust
  • Mantle
  • Core
  • Lithosphere
  • Asthenosphere
  • Convection
  • Divergent boundary
  • Convergent boundary
  • Transform plate boundary
  • Seafloor
  • Seafloor structures
  • Alfred Wegener
  • Plastic flow


  • Fossils are a trace or print of the remains of a plant or animal of a past age preserved in plant or rock.
  • Rocks are the solid mineral materials forming part of the surface of the Earth and other similar planets.
  • A continent is any of the world's main continuous expanses of land (i.e.,, Africa, Antarctica, Asia, Australia, Europe, North America, and South America).
  • The continental shelf is the part of a continent that lies under the ocean and slopes down to the ocean floor.
  • Regions of different continents that share similar fossils and similar rocks suggest that, in the geologic past, those sections of continent were once attached and have since been separated.
  • The shapes of the continents roughly fit together like pieces in a jigsaw puzzle, suggesting that those land masses were once joined and have since separated.
  • The hypothetical land mass that existed when all the continents were joined is called Pangea.
  • The separation of continents by the sequential formation of new seafloor at the center of the ocean is inferred by age patterns in the oceanic crust that increase in age from the center of the ocean to the edges of the ocean.
  • The distribution of seafloor structures (e.g., volcanic ridges at the centers of oceans, trenches at the edges of continents) combined with the patterns of ages of the seafloor (youngest ages at the ridge, oldest ages at the trenches) supports the interpretation that new crust forms at the ridges and then moves away from the ridges as new crust continues to form and that the oldest crust is being destroyed at seafloor trenches.
  • Ridges are underwater mountain systems formed by plate tectonics.
  • Trenches are long, narrow, steep-sided depressions in the ocean floor.
  • The Theory of Continental Drift was first proposed by Alfred Wegener and proposes that part of the Earth's crust slowly drifts atop a liquid core.
  • The Theory of Plate Tectonics states that the outer rigid layer of the Earth is divided into a couple of dozen "plates" that move around across the Earth's surface relative to each other.
  • The layers of the Earth include, from outmost to innermost, the crust, mantle, outer core, and inner core. The crust and upper mantle are broken into moving plates called the lithosphere. The asthenosphere is located below the lithosphere. In the asthenosphere, there is relatively low resistance to plastic flow and convection occurs, causing plates to move.
  • The three types of plate tectonic boundaries include divergent, convergent, and transform plate boundaries.
  • Divergent boundaries occur when two tectonic plates move away from each other.
  • Convergent boundaries occur when two tectonic plates come together.
  • Transform plate boundaries occur when two plates slide past one another.


Students are able to:
  • Articulate a statement that relates a given phenomenon to a scientific idea, including that past plate motions can be described with data from the distribution of fossils and rocks, continental shapes, and seafloor structures.
  • Organize given data in a way that facilitates analysis and interpretation.
  • Analyze the data to identify relationships between the data and Earth's past plate motions.
  • Identify and use multiple valid and reliable sources of data.
  • Use evidence and reasoning to construct an explanation for the given phenomenon, which involves past plate motions.


Students understand that:
  • Maps of ancient land and water patterns, based on investigations of rocks and fossils, make clear how Earth's plates have moved great distances, collided, and spread apart.

Scientific and Engineering Practices

Constructing Explanations and Designing Solutions

Crosscutting Concepts