In general, an atmosphere is a blanket of gases surrounding a planet. Unless otherwise identified, however, the term refers to the atmosphere of Earth, which consists of nitrogen (78%), oxygen (21%), argon (0.93%), and other substances that include water vapor, carbon dioxide, ozone, and noble gases such as neon, which together comprise 0.07%.
An upward movement by Earth's crust in response to the melting of a glacier, which redistributes its vast weight and causes Earth to rebound.
An area of physical geology concerned with the study of landforms, with the forces and processes that have shaped them, and with the description and classification of various physical features on Earth.
The upper part of Earth's continental crust, or that portion of the solid Earth on which human beings live and that provides them with most of their food and natural resources.
The covering of the landscape with large expanses of ice, as during an ice age.
A large, typically moving mass of ice on or adjacent to a land surface.
An area of physical geology devoted to the study of ice, itsforms, and its effects.
The entirety of Earth's water, excluding water vapor in the atmosphere but including all oceans, lakes, streams, groundwater, snow, and ice.
A period of massive and widespread glaciation. Ice ages usually occur in series over stretches of several million years, or even several hundred million years.
An ice formation bigger thana glacier but smaller than an ice sheet. An ice cap typically has an area of less than19,300 sq. mi. (50,000 sq km) and, like an ice sheet, consists of an ice dome, with ice shelves and outlet glaciers at the edges.
A vertical section of ice, usually taken from a deep ice sheet such as that in Antarctica. When studied with the proper techniques and technology, ice cores can reveal past climatic conditions in much the same way that the investigation of tree rings does.
A symmetrical, convex(i.e., like the outside of a bowl) mass of ice, often thicker than 9,800 ft. (3,000 m), usually found at the center of an ice cap or an ice sheet.
A large ice formation, similar to an ice cap except that it is nearly level and lacks an ice dome. There are enormous variations in size for ice fields. Some may be no larger than 1.9 sq. mi. (5 sq km), while at different times in Earth's history, some have been as large as continents.
A vast expanse of ice, usually at least 19,300 sq. mi. (50,000 sq km), that moves outward from its center. Like the smaller ice caps, ice sheets consist of ice domes and outlet glaciers, with outlying ice shelves.
An ice formation at the edge of an ice cap or ice sheet that extends into the ocean, typically ending in cliffs as high as 98 ft. (30 m).
A notable topographicalfeature, such as a mountain, plateau, or valley.
An abbreviation used by earth scientists, meaning million years or megayears. When an event is designated as, for instance, 160 Ma, it usually means 160 million years ago.
A phenomenon in which numerous species cease to exist at or around the same time, usually as the result of a natural calamity.
A hill-like pile of till left behind by a glacier.
Structure or form, or the study thereof.
A rapidly moving stream of ice that extends from an icedome.
The study of the material components of Earth and of the forces that have shaped the planet. Physical geology is one of two principal branches of geology, the other being historical geology.
The temperature at which ice begins to melt under a given amount of pressure. The higher the pressure, the lower the temperature at which water can exist in liquid form.
Elevation and other in equalities on a land surface.
Material deposited at or near Earth's surface from a number of sources, most notably preexisting rock.
A general term for the sediments left by glaciers that lack any intervening layer of melted ice.
The configuration of Earth's surface, including its relief as well as the position of physical features.
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