Plate Tectonics

Dante's View in Death Valley National Park
Dante's View in Death Valley National Park

NPS Photo/ Dale Pate

It is not an exaggeration to paraphrase the biologist Theodosius Dobzhansky and say that 'nothing in geology makes sense except in the light of plate tectonics.' We live on a layer of Earth known as the lithosphere which is a collection of rigid slabs that are shifting and sliding into each other. These slabs are called tectonic plates and fit together like pieces to a puzzle. The shifts and movements of these plates is what shapes our landscape by forming mountain ranges, transforming the ocean floor, and shaping lands near plate boundaries.

Map of Earth's tectonic plates
A map of the tectonic plates of the earth. Where plates collide (convergent boundaries), mountain building and volcanism occurs. Where plates are spreading (divergent boundaries) new crust is being created.
Notice where the continent of India is converging with Asia. This collision is responsible for the Himalayan Mountains.

Modified from: R.J. Lillie. 2005. Parks and Plates.

The motions of the plates have a tremendous ability to shape and deform rocks through a variety of processes that include folding,faulting, extension, and, on a massive scale, mountain building.
Subduction zone diagram
Diagram of oceanic crust being subducted beneath the continental crust.

United States Geological Survey

New crust is constantly being created at rifts zones, or mid-ocean ridges where lava cools as new rock. Crust is also being constantly consumed at subduction zones, where thin and dense oceanic crust slides undernearth thick and (relatively) buoyant continental crust.
Any continetnal material that is towed by the oceanic crust collides with the overriding continental crust. This can include anything from small islands to other continents. When two continents collide, towering mountain ranges form. This is how the Appalachian Mountains formed, millions of years ago.

Plate tectonics is an important geologic concept as it fills in the gaps to Earth's geologic history. The theory of plate tectonics helps explain the formation of mountain ranges, volcanism, earthquakes and the features associated with active plate boundaries. Tectonic processes shape the landscape and form some of the most spectacular structures found in national parks, from the highest peaks in the Rocky Mountains to the faulted mountains and valleys in the Basin and Range Province.

Below are a variety of educational materials to help students gain an understanding of continental drift, faulting, and the processes associated with plate tectonics.


Educational Resources

Hot Spot

Students learn about the Mantle Plume Theory, plate tectonics, and Idaho geography by experimenting with a map of Idaho.
Diagram of Grand Teton normal fault
The Teton Range, in Grand Teton National Park (Wyoming), rises more than 2,100 m (6,900 ft) above the floor of Jackson Hole. This range is part of the upthrown footwall block of the fault, while Jackson Hole is situated on the downdropped hanging wall.

Trista L. Thornberry-Ehrlich, Colorado State University. Modified from: R.J. Lillie. 2005. Parks and Plates.


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