The program covers convergent boundaries, subduction, hotspots, and the debate over what drives plate motion. Mountain Building This program erodes the myth of the mountain as a solid, permanent structure.

Animations are used to illustrate the process of orogeny (mountain building) through accretion and erosion, as well as the role of plate tectonics, the rock cycle, and how different types of rock are formed in the course of mountain building. Earth's Structures A visit to the Grand Canyon lays the foundation for this exploration of rock layers and deformation.

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This program examines the traces left by early plants, animals, and single-celled organisms and follows the progression of life forms over time.

Connections are drawn between atmospheric gases, climate change, rock formation, biological functions, and mass extinctions. Minerals: The Materials of Earth Minerals have been indispensable to human civilization.

However, this notion changed dramatically over time, especially after the invention of the telescope.

This program traces the development of astronomical theory with discussions of the discoveries of Copernicus, Galileo, Kepler, and Newton.

The program provides images of glaciers and glacial landforms such as moraines, and discusses how study of glaciers may help us understand ice ages and the greenhouse effect. Waves, Beaches and Coasts This program shows the dynamic interaction of two geologic agents: rocky landmasses and the energy of the ocean.

Aspects of waves — their types, parts, movement, and impact on the shore — are illustrated.

This program looks at the variety of minerals, their atomic and crystalline structures, and their physical properties such as hardness and luster.

Petrologists' methods of sectioning rocks are shown, and gems, precious metals, ore excavation, and the value of silicates are discussed. Volcanism Volcanoes provide clues about what is going on inside Earth. Intrusive Igneous Rocks Most magma does not extrude onto Earth's surface but cools slowly deep inside Earth.

This program traces the development of plate tectonics, beginning with the contributions and methods of geologist Alfred Wegener.

Sea-floor spreading, continental drift, paleomagnetism, and the primordial supercontinent Pangaea are some of the topics covered. Plate Dynamics This program examines the movement and interaction of tectonic plates, which account for a vast array of geologic formations and phenomena — from California's San Andreas Fault to the Rift Valley of eastern Africa.

Faults, waves, and the transfer of energy from the epicenter are explained, and histories of the seismograph and Richter scale are presented.