Natural resources are materials that form naturally on Earth and that are used by people. Natural resources include plants, animals, other living things, rocks, minerals, oil, gas, water, sunlight, and air. Natural resources are important because people rely on them for food and water; to make clothing; to build shelters, transportation systems, and products; and for energy. Everything that we use or make is made of natural resources.
A renewable resource is a natural resource that is replaced in nature at the same rate that it is used, or at a greater rate. Examples of renewable resources include sunlight, water, food, trees, and renewable energy sources such as solar, wind, hydroelectric, and geothermal energy.
A nonrenewable resource is a natural resource that is not formed quickly by natural processes. Examples of nonrenewable resources include minerals, metals, and fossil fuels such as petroleum, coal, and natural gas. Nonrenewable resources may be reused or recycled, but they cannot be replaced on the timescale of a human life.
A resource that is generally renewable can be considered nonrenewable if it is used up faster than it is replaced. For example, harvesting trees without replanting them, or harvesting trees faster than they can grow back, turns trees into a nonrenewable resource.
Different natural resources are formed in different ways. All natural resources are formed by natural geological or biological processes. For example, coal is an energy resource. It formed when swamp plants were buried, heated, and squeezed for millions of years. Soil is a natural resource that are made of rock that has weathered in place or from sediments that have been deposited by wind or water.
Different natural resources are found in different parts of the world. They are not distributed evenly over the globe. Because different resources form in different ways, the types of rock, mineral , and soil resources that are found in a certain place depends on the geologic history and the climate history of the region. For example, limestone is found in places that were once warm, shallow seas. Plant and animal resources are found in environments where those organisms can live. Certain trees are found only in certain climates, for example. Fish are found in water, but not on land.
Landscapes also form due to natural processes called weathering, erosion, and deposition. These processes act together in a cycle to change Earth’s surface. Weathering wears down the earth; erosion moves the weathered earth materials; and deposition builds up the earth.
Weathering is the chemical and physical breakdown of rock. The weathered rock is broken down into sediment, or small particles of organic matter. One kind of weathering is exfoliation. This type of weathering peels away layers of rock in sheets.
Erosion involves moving sediment, or weathered rock, from one place to another. Wind can cause erosion. Wind strips away topsoil, which prevents plants from growing. An area prone to wind erosion can eventually lose all of its soil. Soil erosion is especially detrimental to agricultural activities. As soil cover is reduced, land becomes less suitable for crop farming. Water can also cause erosion. The water of the Rio Grande has eroded the canyon walls.
Erosion can have a substantial impact on river ecosystems. Eroded materials can be deposited in the inner edge of meanders, or twists, in rivers. Meanders can eventually become clogged with sediment and be cut off from the river. The cut-off bodies of water are called oxbow lakes. The town of Oxbow Lake is named for a lake that once was a meander of the Rio Grande.
A river with fewer meanders flows faster, erodes the soil more quickly, and provides water for less of the surface area of the surrounding land. Waves on the Gulf Coast are also a cause of erosion. After Hurricane Katrina, much of Texas’s beachfront was lost to wave erosion.
Deposition involves the placement of weathered rock, or sediment, at a site other than its place of origin. The actions of waves on the shores of the Texas coastline, such as at Galveston Beach, pull sediments out into the Gulf of Mexico, where they are deposited in the forms of sand bars and islands.