America has more coal than any other fossil fuel resource. The U.S. also has more coal reserves than any other single country in the world. In fact, 25% of all the known coal in the world is in the United States. Large coal deposits can be found in 38 of the 50 states.
The Origins of Coal
Coal is a fossil fuel that formed from the remains of vegetation that grew as long as 400 million years ago. Contrary to what some people believe, coal is not the remains of dead dinosaurs.
Coal is sometimes referred to as "buried sunshine" because the plants, which formed coal, captured energy from the sun through photosynthesis to create the compounds that make up plant tissues. The most important element in the plant material is carbon, which gives coal most of its energy.
Most of our coal was formed about 300 million years ago, when much of the earth was covered by steamy swamps. As plants and trees died, their remains sank to the bottom of the swampy areas, accumulating layer upon layer and eventually forming a soggy, dense material called peat.
Over long periods of time, the makeup of the earth’s surface changed, and seas and great rivers caused deposits of sand, clay and other mineral matter to accumulate, burying the peat. Sandstone and other sedimentary rocks were formed, and the pressure caused by their weight squeezed water from the peat. Increasingly deeper burial and the heat associated with it gradually changed the material to coal. Scientists estimate that from 3 to 7 feet of compacted plant matter was required to form 1 foot of bituminous coal.
Coal formation is a continuing process (some of our newest coal is a mere 1 million years old). Today, in areas such as the Great Dismal Swamp of North Carolina and Virginia, the Okefenokee Swamp of Georgia, and the Everglades in Florida, plant life decays and subsides, eventually to be covered by silts and sands and other matter. Perhaps millions of years from now, those areas will contain large coal beds.