Guided Notes about Natural Resources Chapter 25, Section 1 1. All living things must have certain resources to grow, develop, maintain life processes, and reproduce. In addition to food and water, most animals also need shelter. 2. Natural resources include Earth’s air, water, and land; all living things and nutrients, rocks and minerals. 3. Renewable resources are natural resources that it is possible to use indefinitely without causing a reduction in the supply. They include fresh air, surface water, groundwater, fertile soil, elements that cycle through Earth’s systems, and living things. 4. Resources that exist in an inexhaustible supply, such as solar energy, also are renewable resources. 5. Renewable resources are replaced through natural processes at a rate that is equal to, or greater than, the rate at which they are being used. 6. Sustainable yield is the replacement of renewable resources at the same rate at which they are consumed. 7. Sunlight is considered to be a renewable resource because it will be available for the next 5 billion years. 8. Nonrenewable resources are resources that exist in a fixed amount in Earth’s crust and can only be replaced by processes that take hundreds of millions of years. Fossil fuels, gemstones, and metallic elements are nonrenewable. They are exhaustible because they are being used at a much higher rate than they rate at which they were formed. 9. Natural resources are not distributed evenly on Earth. The wealth of a country is determined by the availability of natural resources. 1. Land provides places for organisms to live and interact. It also provides spaces for the growth of crops, forests, grasslands, and for wilderness areas. 2. 42 percent of the land in the United States is public land and are federally administered to protect timber, grazing areas, minerals, and energy resources. 3. National wildlife refuges provide protection of habitats and breeding areas for wildlife, including endangered species. 4. It can take 1000 years to form a few centimeters of soil, yet it can be lost in minutes as a result of erosion by wind or water. Plowing and leaving bare ground without plant cover can increase topsoil loss. 5. The loss of topsoil can lead to desertification, which is the process by which productive land becomes desert. This can be prevented by reducing overgrazing and by planting trees and shrubs to anchor soils and retain water. 6. Aggregate is a mixture of gravel, sand, and crushed stone that naturally accumulates on the Earth’s surface. Aggregates are found in floodplains or alluvial fans, or are deposited by glacial activity. 7. An ore is a natural resource that can be mined at a profit. The value of an ore on the market is greater than the cost of its extraction. 8. The most important sources of metallic ore deposits are hydrothermal fluids. Hydrothermal veins commonly form along faults and joints. Which minerals are often found in placer deposits? Gold, diamonds, platinum, and gemstones