| Mantle | | Of, relating to, or involving a catastrophe. (Catastrophic) |
| Hypothesis | | The spherical mass, largely metallic iron, at the center of the Earth. (Core) |
| Principle | | The outer portion of Earth’s core, which is molten. (Outer Core) |
| Earth System | | A scientific statement that some aspect of nature is always observed to happen in the same way and that no deviations have ever been seen. (Law) |
| Athenosphere | | The thick shell of dense, rocky matter that surrounds the core. (Mantle) |
| Theory | | Any system with a boundary that allows the passage in or out of energy but not of matter. (Closed System) |
| Law | | The central, solid portion of Earth’s core. (Inner Core) |
| Moho | | The use of evidence that can be seen and tested by anyone who has the means to do so, consisting often of observation, formation of a hypothesis, testing of the hypothesis and formation of a theory, formation of a law, and continued reexamination. (Scientific Method) |
| System | | The science of our planet. (Geology) |
| Lithosphere | | Grand unifying theory of geology saying that Earth’s outermost 100km “eggshell” (the lithosphere) is cracked, composed of about a dozen pieces (“plates”), which float on the hot, deformable athenoshpere, moving ponderously in various directions, spreading apart, slowly colliding, and grinding past another. (Plate Tectonics Theory) |
| Gradualism | | The study of the processes that operate at or beneath the surface of Earth, and the materials on which those processes operate. (Physical Geology) |
| Physical Geology | | An unproved explanation for the way things happen. (Hypothesis) |
| Continental Crust | | The outer 100 km of solid Earth, where rocks are harder and more rigid than those in the plastic athenosphere. (Lithosphere) |
| Plate Tectonics Theory | | Any system that has a boundary that prevents the passage in or out of energy and matter. (Isolated System) |
| Crust | | The crust between the oceans. (Oceanic Crust) |
| Inner Core | | The layer of the mantle where rocks are relatively ductile and are easily deformed. It lies at a depth of 100 to 350 km below the surface. (Athenosphere) |
| Catastrophic | | The outermost and thinnest of Earth’s compositional layers, which consists of rocky matter that is less dense than the rocks of the mantle below. (Crust) |
| Core | | The primary unit in a time-stratigraphic sequence of rocks. (System) |
| Open System | | Any system that has a boundary that allows the passage in or out of both energy and matter. (Open System) |
| Isolated System | | A hypothesis that has been examined and found to withstand numerous tests. (Theory) |
| Benioff Zone | | A statement that some aspect of nature is always observed to happen in the same way and that not deviations have ever been observed. (Principle) |
| Outer Core | | The assemblage of all of Earth’s parts and the relationships between them. (Earth System) |
| Geology | | The view that speciation proceeds by imperceptibly small, cumulative steps over long periods of time rather than by abrupt, major changes. (Gradualism) |
| Closed System | | A narrow, well-defined zone of deep earthquake foci beneath a sea floor. (Benioff Zone) |
| Oceanic Crust | | The part of the Earth’s crust that comprises the continents, which has an average thickness of 45 km. (Continental Crust) |
| Scientific Method | | The seismic discontinuity that marks the base of the crust. (Moho) |
