They based their idea of continental drift on several lines of evidence: fit of the continents, paleoclimate indicators, truncated geologic features, and fossils.

Glacial deposits, specifically till, of the same age and structure are found on many separate continents that would have been together in the continent of Pangaea. Fossil evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart.

The main reason that Wegener’s hypothesis was not accepted was because he suggested no mechanism for moving the continents. He thought the force of Earth’s spin was sufficient to cause continents to move, but geologists knew that rocks are too strong for this to be true.

Continental drift, large-scale horizontal movements of continents relative to one another and to the ocean basins during one or more episodes of geologic time. This concept was an important precursor to the development of the theory of plate tectonics, which incorporates it.

Plate tectonics explains why Earth’s continents are moving; the theory of continental drift did not provide an explanation. Therefore, the theory of plate tectonics is more complete.

Alfred Wegener

Why do plates move? One explanation for plate movements is slab pull. Plates are extremely heavy so gravity acts upon them, pulling them apart. Alternatively, as shown in the diagram, convection currents under the Earth’s crust transfer heat, which rises through the surface and cools back down in a circular motion.

Modern continents hold clues to their distant past. Evidence from fossils, glaciers, and complementary coastlines helps reveal how the plates once fit together. Other life dispersed to new areas as continents reconnected, oceans narrowed, or chains of volcanic islands formed. …

boundary

What happens when two continental plates collide? Instead, a collision between two continental plates crunches and folds the rock at the boundary, lifting it up and leading to the formation of mountains and mountain ranges.

There are three main types of plate boundaries:

• Convergent boundaries: where two plates are colliding. Subduction zones occur when one or both of the tectonic plates are composed of oceanic crust.
• Divergent boundaries – where two plates are moving apart.
• Transform boundaries – where plates slide passed each other.