| A | B |
|---|
| Earth System | All of the Nonliving things, living Things, and processes that make up the planet Earth. |
| Atmosphere | A mixture of gases that surrounds a planet, moon, or other celestial body. |
| Cryosphere | Those portions of Earth's surface where water occurs in a solid form. |
| Geosphere | The mostly solid, rocky part of Earth; extends from the center of the core to the surface of the crust. |
| Biosphere | The part of Earth where life exists; includes all of the living organisms on Earth. |
| Hydrosphere | The portion of Earth that is water. |
| Energy Budget | The net flow of energy into and out of a system. |
| Physical Weathering | The mechanical breakdown of rocks into smaller pieces that is caused by natural processes and that does not change the chemical composition of the rock material. |
| Weathering | The natural process by which atmospheric and environmental agents, such as wind, rain, and temperature changes, disintegrate and decompose rocks. |
| Exfoliation | The process by which the outer layers of rock slowly peel away due to pressure changes. |
| Abrasion | The process by which rock is reduced in size by the scraping action of other rocks driven by water, wind, and gravity. |
| Chemical Weathering | The chemical breakdown and decomposition of rocks by natural processes in the environment. |
| Oxidation | A chemical reaction in which a material combines with oxygen to form new material; in geology, it is a form of chemical weathering. |
| Acid Precipitation | Rain, sleet, or snow that contains a high concentration of acids. |
| Stalactites | The dissolved rock material is carried in water and deposited on the ceiling of an underground cavern. |
| Stalagmites | The dissolved rock material is carried in water and deposited on the floor of an underground cavern. |
| Uniformitarianism | A principle that geologic processes that occurred in the past can be explained by current geologic processes. |
| Fossils | The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock. |
| Trace Fossils | A fossilized structure, such as a footprint or a coprolite, that formed in sedimentary rock by animal activity on or within soft sediment. |
| Fossil Record | All of the fossils that have been discovered on Earth. |
| Pangaea | The supercontinent that formed 300 million years ago and that began to break up 200 million years ago according to theory. |
| Climate | The weather conditions in an area over a long period of time. |
| Ice Core | A long cylinder of ice obtained from drilling through ice caps or ice sheets; used to study past climates. |
