Dynamic Earth

5. A naturally occurring, inorganic, crystalline solid that has characteristic physical properties and a narrowly defined chemical composition.
6. The science concerned with the study of Earth materials (minerals and rocks), surface and internal processes, and Earth history.
8. rock Any rock that has been changed from its original condition by heat, pressure, and the chemical activity of fluids, as in marble and slate.
10. cycle A group of processes through which Earth materials may pass as they are transformed from one major rock type to another.
12. A solid aggregate of one or more minerals, as in limestone and granite, or a consolidated aggregate of rock fragments, as in conglomerate, or masses of rocklike materials, such as coal and obsidian.
15. tectonic theory The theory holding that large segments of Earth's outer part (lithospheric plates) move relative to one another.
17. Remains or traces of prehistoric organisms preserved in rocks. (See also body fossil and trace fossil)
18. The part of the mantle that lies below the lithosphere; it behaves plastically and flows slowly.
19. rock Any rock composed of sediment, such as limestone and sandstone.

1. An explanation for some natural phenomenon that has a large body of supporting evidence. To be scientific, a theory must be testable ? for example, plate tectonic theory.
2. method A logical, orderly approach that involves gathering data, formulating and testing hypotheses, and proposing theories.
3. of uniformitarianism A principle holding that we can interpret past events by understanding present-day processes, based on the idea that natural processes have always operated in the same way.
4. rock Any rock formed by cooling and crystallization of magma or lava or the consolidation of pyroclastic materials.
7. Earth's outer, rigid part, consisting of the upper mantle, oceanic crust, and continental crust.
9. A provisional explanation for observations that is subject to continual testing. If well supported by evidence, a hypothesis may be called a theory.
11. Earth's outermost layer; the upper part of the lithosphere that is separated from the mantle by the Moho; divided into continental and oceanic crust.
13. The thick layer between Earth's crust and core.
14. The interior part of Earth beginning at a depth of 2900 km that probably consists mostly of iron and nickel.
15. An individual segment of the lithosphere that moves over the asthenosphere.
16. A combination of related parts that interact in an organized fashion; Earth systems include the atmosphere, hydrosphere, biosphere, and solid Earth.