Plate Tectonics

Some tectonic plates move faster than their underlying convection currents

Like a chain slipping off a ledge, as tectonic plates sink, their weight can pull the rest of the trailing plate forward, accelerating their movement. Plates can also break apart and fall, creating a suction effect that drives movement, resembling leaves following a passing car.

Earth’s major tectonic plates make up 95% of its surface

Tectonic plates are pieces of Earth’s lithosphere, which consists of the crust and the solid, upper layer of the mantle. Segments of major plates can break and form minor or microplates, whose total number varies based on ongoing geological activity.

Watch 1 billion years of tectonic plate movement in 40 seconds

Researchers at the University of Sydney developed the model, incorporating changing plate boundaries rather than just moving continents, to better understand the changes to biological and climatic systems throughout Earth’s history.

The formation and breakup of Pangaea altered Earth’s geology and biodiversity

Coming from the Greek words for “all” (pan) and “Earth” (gaia), the supercontinent existed from about 320 million to 195 million years ago. The tectonic activity that split Pangaea into today’s continents may one day bring the continents back together, forming Pangaea Proxima.

The discovery of the Mid-Atlantic Ridge was initially dismissed as ‘girl talk’

Marie Tharp identified the structure when mapping the ocean floor using sonar data, but her colleague, who did not favor continental drift, was unconvinced. Famed filmmaker Jacques Cousteau even tried to disprove her work with underwater footage, only to validate her maps.

The theory of plate tectonics first emerged from the theory of continental drift

German meteorologist Alfred Wegener proposed that the continents were all one giant landmass in the past, which he named Pangaea. Despite geological and climate evidence suggesting continental movement, his theory was dismissed until the 1960s.

How facts, hypotheses, theories, and laws in science differ from everyday language

Facts are observations of the world, and they can be pooled together for a given phenomenon to develop a hypothesis—a proposed explanation consistent with observations that requires further investigation. Experiments and additional data can rule out many hypotheses or graduate a proposed explanation into a widely accepted and validated theory.

Continental drift is supported by matching evidence across disconnected continents

Mesosaurus fossils are found in South America and Africa, but these freshwater creatures could not have travelled across the ocean between continents. Rock layers in the Appalachian Mountains match those seen in Europe, indicating that the mountain belts were once connected.

Convection flows in Earth’s mantle drive the movement of tectonic plates

These processes transfer heat from Earth’s core to the surface via rising magma plumes, while cooler, denser rock falls into the mantle at rates similar to human fingernail growth. These rates are determined by combining seismic data with computer simulations to model Earth’s interior.

Mid-ocean ridges are underwater volcano systems where tectonic plates diverge

New ocean crust is formed at these ridges as magma rises from Earth’s mantle and fills the space between the spreading plates. The speed of divergence influences ridge shape, with slow spreads forming rugged valleys and fast spreading creating smooth, wide slopes.