chapter 8Review
In this chapter, we have examined how geologic processes such as plate tectonics, earthquakes, and volcanism have led to the differential distribution of elements and minerals on the surface of Earth. These geologic processes, which have occurred at different rates over long periods of time, have led to the formation of different rocks and minerals on or near the surface of Earth. Rocks and minerals have undergone weathering at different rates and have been eroded and deposited elsewhere on Earth. This has been one of the contributors to soil formation. Soils are a membrane that covers much of the land surface on Earth and these soils contain a mixture of geologic material from below and organic material from plants and animals from above. We have also examined how the actions involved in removal of valuable mineral resources from on top and below the surface of Earth have affected a number of environmental processes.
Core Mantle Magma Asthenosphere Lithosphere Crust Hot spot Plate tectonics Tectonic cycle Subduction Volcano Divergent plate boundary Seafloor spreading Convergent plate boundary Transform fault boundary Fault Seismic activity Fault zone Earthquake Epicenter Richter scale Rock cycle Igneous rock Intrusive igneous rock Extrusive igneous rock Fracture Sedimentary rock Metamorphic rock Physical weathering Chemical weathering Acid precipitation Acid rain Erosion Parent material Soil degradation Horizon O horizon A horizon Topsoil E horizon B horizon C horizon Cation exchange capacity (CEC) Base saturation Crustal abundance Ore Metal Reserve Strip mining Mining spoils Tailings Open-pit mining Mountaintop removal Placer mining Subsurface mining | The layer of Earth above the core, containing magma. Rock formed directly from magma. The sum of the processes that build up and break down the lithosphere. Rock that forms when sediments such as muds, sands, or gravels are compressed by overlying sediments. The process of one crustal plate passing under another. An area where plates move toward one another and collide. A concentrated accumulation of minerals from which economically valuable materials can be extracted. The removal of strips of soil and rock to expose ore. The least-weathered soil horizon, which always occurs beneath the B horizon and is similar to the parent material. The frequency and intensity of earthquakes experienced over time. Rock that forms when magma cools above the surface of Earth. The average concentration of an element in Earth’s crust. A fracture in rock caused by a movement of Earth’s crust. 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. The mechanical breakdown of rocks and minerals. The theory that the lithosphere of Earth is divided into plates, most of which are in constant motion. A scale that measures the largest ground movement that occurs during an earthquake. Frequently the top layer of soil, a zone of organic material and minerals that have been mixed together. Also known as Topsoil. In geology, the chemically distinct outermost layer of the lithosphere. Precipitation high in sulfuric acid and nitric acid from reactions between water vapor and sulfur and nitrogen oxides in the atmosphere. Also known as Acid rain. A mining technique that uses a large visible pit or hole in the ground. A zone of leaching, or eluviation, found in some acidic soils under the O horizon or, less often, the A horizon. Unwanted waste material created during mining. Also known as Mining spoils. The process of looking for minerals, metals, and precious stones in river sediments. Mining techniques used when the desired resource is more than 100 m (328 feet) below the surface of Earth. Precipitation high in sulfuric acid and nitric acid from reactions between water vapor and sulfur and nitrogen oxides in the atmosphere. Also known as Acid precipitation. The breakdown of rocks and minerals by chemical reactions, the dissolving of chemical elements from rocks, or both. The loss of some or all of a soil’s ability to support plant growth. Rock that forms when sedimentary rock, igneous rock, or other metamorphic rock is subjected to high temperature and pressure. Frequently the top layer of soil, a zone of organic material and minerals that have been mixed together. Also known as A horizon. An area beneath the ocean where tectonic plates move away from each other. Molten rock. A vent in the surface of Earth that emits ash, gases, or molten lava. A large expanse of rock where a fault has occurred. Unwanted waste material created during mining. Also known as Tailings. The geologic cycle governing the constant formation, alteration, and destruction of rock material that results from tectonics, weathering, and erosion, among other processes. The formation of new ocean crust as a result of magma pushing upward and outward from Earth’s mantle to the surface. The proportion of soil bases to soil acids, expressed as a percentage. The innermost zone of Earth’s interior, composed mostly of iron and nickel. It includes a liquid outer layer and a solid inner layer. In resource management, the known quantity of a resource that can be economically recovered. The exact point on the surface of Earth directly above the location where rock ruptures during an earthquake. The rock material from which the inorganic components of a soil are derived. In geology, a place where molten material from Earth’s mantle reaches the lithosphere. An element with properties that allow it to conduct electricity and heat energy, and to perform other important functions. A horizontal layer in a soil defined by distinctive physical features such as texture and color. In geology, a crack that occurs in rock as it cools. The layer of Earth located in the outer part of the mantle, composed of semi-molten rock. The ability of a particular soil to absorb and release cations. Igneous rock that forms when magma rises up and cools in a place underground. The organic horizon at the surface of many soils, composed of organic detritus in various stages of decomposition. A soil horizon composed primarily of mineral material with very little organic matter. The outermost layer of Earth, including the mantle and crust. The physical removal of rock fragments from a landscape or ecosystem. A mining technique in which the entire top of a mountain is removed with explosives. An area where tectonic plates move sideways past each other. |
Module 24 Mineral Resources and Geology
Describe the formation of Earth and the distribution of critical elements on Earth.
Earth formed from cosmic dust in the solar system. As it cooled, heavier elements, such as iron, sank toward the core, while lighter elements, such as silica, floated toward the surface. These processes have led to an uneven distribution of elements and minerals throughout the planet.
Define the theory of plate tectonics and discuss its relevance to the study of the environment.
Earth is overlain by a series of plates that move at rates of a few millimeters per year. Plates can move away from each other, move toward each other, or slide past each other. One plate can be subducted under another. These tectonic processes create mountains, earthquakes, and volcanoes.
Describe the rock cycle and discuss its importance in environmental science.
Rocks are made up of minerals, which are formed from the various chemical elements in Earth’s crust. The processes of the rock cycle lead to the formation, breakdown, and recycling of rocks.
Module 25 Weathering and Soil Science
Understand how weathering and erosion occur and how they contribute to element cycling and soil formation.
Physical weathering is the mechanical breakdown of rocks and minerals while chemical weathering is a result of chemical reactions. Both occur as a result of natural processes and can be accelerated by human activities. Erosion is the physical removal of rock fragments and weathering products that are subsequently deposited elsewhere.
Explain how soil forms and describe its characteristics.
Soil forms as the result of physical and chemical weathering of rocks and the gradual accumulation of organic detritus from the biosphere. The factors that determine soil properties are parent material, climate, topography, soil organisms, and time. The relative abundances of sand, silt, and clay in a soil determine its texture.
Describe how humans extract elements and minerals and the social and environmental consequences of these activities.
Concentrated accumulations of minerals from which economically valuable materials can be extracted are called ores. Ores are removed by surface or subsurface mining operations. Surface mining generally results in greater environmental impacts, whereas subsurface mining is more dangerous to miners. With the exception of coal mining, legislation directly related to mining does not address most environmental considerations.