Geologic Timescale


Earth's crust, the surface layer of the planet, is not solid and unbroken. The forces that rage inside the planet have fractured this brittle layer.


Floodplains are landscapes shaped by running water. As streams and their larger forms, rivers, flow across the surface of land, they transport eroded rock and other material.

Geyser and Hot Spring

An eponym (pronounced EH-puh-nim) is something or someone that gives its name to everything of its type. In geology, two general landforms derive their names from those of specific examples.

Glacial Landforms and Features

During the last Ice Age, which ended approximately 10,000 years ago, 32 percent of Earth's land area was covered with glaciers. At present, glaciers cover roughly 10 percent of the land area.

Landslide and Other Gravity Movements

Gravity is the physical force of attraction between any two objects in the universe. One of the four fundamental forces (the others are electromagnetism and the strong and weak forces), gravity affects all objects on Earth.

Mesa and Butte

Spanish explorers in the mid-sixteenth century ranged over the American Southwest. They had come north from Mexico, looking for gold and gems and the legendary Seven Cities of Cibola (pronounced SEE-bow-lah), allegedly filled with such treasures.

Meteorite Crater

In July 1994, pieces of the comet Shoemaker-Levy 9 slammed into thes outhern hemisphere of the planet Jupiter at a speed of 37 miles (60 kilometers) per second. Professional and amateur astronomers around the world witnessed the spectacular and historic event.


Mountains loom large on the face of the planet. These rocky landforms, which tower over all others on Earth, are places of extreme temperatures and winds.