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| 7746479507 | Core | the innermost zone of Earth's interior, composed mostly of iron and nickel. It includes a liquid outer layer and a solid inner layer. |  | 0 |
| 7746479508 | Mantle | the layer of Earth above the core, containing magma. |  | 1 |
| 7746479509 | Magma | molten rock |  | 2 |
| 7746479510 | Asthenosphere | the layer of Earth located in the outer part of the mantle, composed of semi-molten rock. |  | 3 |
| 7746479511 | Lithosphere | the outermost layer of Earth, including the mantle and crust. |  | 4 |
| 7746479512 | Crust | In geology, the chemically distinct outermost layer of the lithosphere. |  | 5 |
| 7746479513 | Hot spot | In geology, a place where molten material from Earth's mantle reaches the lithosphere. |  | 6 |
| 7746479514 | Plate tectonics | the theory that the lithosphere of Earth is divided into plates, most of which are in constant motion. |  | 7 |
| 7746479515 | Tectonic cycle | The sum of the processes that build up and break down the lithosphere. |  | 8 |
| 7746479516 | Subduction | the processes of one crustal plate passing under another. |  | 9 |
| 7746479517 | Volcano | a vent in the surface of the Earth that emits ash, gases, or molten lava. |  | 10 |
| 7746479518 | Divergent plate boundary | an area beneath the ocean where tectonic plates move away from each other. |  | 11 |
| 7746479519 | Seafloor spreading | the formation of new ocean crust as a result of magma pushing upward and outward from Earth's mantle to the surface. |  | 12 |
| 7746479520 | Convergent plate boundary | an area where plates move toward one another and collide. |  | 13 |
| 7746479521 | Transform fault boundary | an area where tectonic plates move sideways past each other. |  | 14 |
| 7746479522 | Fault | a fracture in rock caused by a movement of Earth's crust. |  | 15 |
| 7746479523 | Seismic activity | the frequency and intensity of earthquakes experienced over time. |  | 16 |
| 7746479524 | Fault zone | a large expanse of rock where a fault has occurred. |  | 17 |
| 7746479525 | Earthquake | the sudden movement of Earth's crust caused by a release of potential energy along a geologic fault and usually causing a vibration or trembling at Earth's surface. |  | 18 |
| 7746479526 | Epicenter | the exact point on the surface of Earth directly above the location where rock ruptures during an earthquake. |  | 19 |
| 7746479527 | Richter scale | a scale that measure the largest ground movement that occurs during an earthquake. |  | 20 |
| 7746479528 | Rock cycle | the geologic cycle governing the constant formation, alteration, and destruction of rock material that results from tectonics, weathering, and erosion, among other processes. |  | 21 |
| 7746479529 | Igneous rock | rock formed directly from magma. |  | 22 |
| 7746479530 | Intrusive igneous rock | igneous rock that forms when magma rises up and cools in a place underground. |  | 23 |
| 7746479531 | Extrusive igneous rock | rock that forms when magma cools above the surface of Earth. |  | 24 |
| 7746479532 | Fracture | In geology, a crack occurs in rock as it cools. |  | 25 |
| 7746479533 | Sedimentary rock | rock that forms when sediments such as muds, sands, or gravels are compressed by overlying sediments. |  | 26 |
| 7746479534 | Metamorphic rock | rock that forms when sedimentary rock, igneous rock, or other metamorphic rock is subjected to high pressure and temperature. |  | 27 |
| 7746479535 | Chemical weathering | the breakdown of rocks and minerals by chemical reactions, the dissolvingof chemical elements from rocks, or both. |  | 28 |
| 7746479536 | Acid precipitation | precipitation high in sulfuric acid and nitric acid from reactions between water vapor and sulfur and nitrogen oxides in the atomosphere. Also known as Acid rain |  | 29 |
| 7746479537 | Physical Weathering | the mechanical breakdown of rocks and minerals | 30 | |
| 7746479538 | Erosion | the physical removal of rock fragments from a landscape or ecosystem. |  | 31 |
| 7746479539 | Parent material | the rock material from which the inorganic components of soil are derived. |  | 32 |
| 7746479540 | Soil degration | the loss of some or all of a soil's ability to support plant growth. | 33 | |
| 7746479541 | Horizon | a horizontal layer in soil defined by distinctive physical features such as texture and color. |  | 34 |
| 7746479542 | O horizon | the organic horizon at the surface of many soils, composed of organic detritus in various stages of decomposition. |  | 35 |
| 7746479543 | A horizon | frequently the top layer of soil, a zone of organic material and minerals that have been mixed together. Also known as topsoil. | | 36 |
| 7746479544 | E horizon | a zone of leaching, or elevation, found in some acidic soils under the O horizon, or less often, the A horizon. | | 37 |
| 7746479545 | B horizon | a soil horizon composed primarily of mineral material with very little organic matter. | | 38 |
| 7746479546 | C horizon | the least-weathered soil horizon, which always occurs beneath the B horizon and is similar to the parent material. | | 39 |
| 7746479547 | Cation exchange capacity (CEC) | the ability of a particular soil to absorb and release cations. |  | 40 |
| 7746479548 | Base saturation | the proportion of soil bases to soil acids, expressed as a percentage. |  | 41 |
| 7746479549 | Crustal abundance | the average concentration of an element in Earth's crust. | 42 | |
| 7746479550 | Ore | a concentrated accumulation of minerals from which economically valuable materials can be extracted |  | 43 |
| 7746479551 | Metal | an element with properties that allow it to conduct electricity and heat energy, and to perform other important functions. |  | 44 |
| 7746479552 | Reserve | in resource management, the known quantity of a resource that can be economically recovered. | 45 | |
| 7746479553 | Strip mining | the removal of strips of soil and rock to expose ore. |  | 46 |
| 7746479554 | Mining spoils | unwanted waste material created during mining. Also known as Tailings | 47 | |
| 7746479555 | Open-pit mining | a mining technique that uses a large visible pit or hole in the ground |  | 48 |
| 7746479556 | Mountaintop removal | a mining technique in which the entire top of a mountain is removed with explosives. |  | 49 |
| 7746479557 | Placer mining | the process of looking for minerals, metals, and precious stones in river sediments. |  | 50 |
| 7746479558 | Subsurface mining | mining techniques used when the desired resource is more than 100 meters (328 feet) below the surface of Earth. |  | 51 |
