Geography

2. The most common sedimentary rock; it is lithified calcium carbonate; very susceptible to chemical weathering by acids in the environment, including carbonic acid in rainfall.
4. The deposition of a chemical compound by reaction with water.
6. A type of desert biome found at higher latitudes than cold deserts, occurring mainly in the very cold, dry climates of Greenland and Antarctica.
8. A process that earlier amplifies or reduces a climate trend toward either warming or cooling.
11. A boundary transition zone between adjoining ecosystems that may vary in width and represent areas of tension as similar species of plants and animals compete for the resources.
12. A technique that uses the atomic structure of chemical elements, specifically the relative amounts of their isotopes, to identify the channel composition of past oceans and ice masses.
14. An open-ended, logarithmic scale that estimates earthquake amplitude magnitude.
16. A sharp release of energy that sends waves travelling through Earth's crust at the moment of rupture along a fault or in association with volcanic activity.
18. The mechanism driving movement of the continents; associated with upwelling flows of magma along the worldwide system of mid-ocean ridges.
20. An unstable isotope that decays, or breaks down, into a different element, emitting radiation in the process.

1. Information about past environments that represent changes in climate, such as isotope analysis or tree ring dating.
3. A large-scale, stable, terrestrial or aquatic ecosystem classified according to the predominant vegetation type and the adaptations of particular organisms to that environment.
5. Magma that issues from volcanic activity into the surface; the extrusive rock that results when magma solidifies.
7. The consolidated or unconsolidated material from which soils develop, ranging from unconsolidated sediments and weathered rock to bedrock.
9. Molten rock from beneath Earth's surface; fluid, gaseous under tremendous pressure, and either intruded into existing crustal rock or extruded into the surface as lava.
10. The mountainous landform at the end of magma conduit, which rises from below the crust and vents to the surface.
13. The chemical breakdown, always in the presence of water, of the constituent minerals in rock.
15. Any process that wears away or rearranges landforms.
17. A biome in the northernmost portions of North America and Northern Europe and Russia, featuring low, ground level herbaceous plants as well as some woody plants.
19. Elevation differences in a local landscape; an expression of local height differences of landforms.