There are economic reasons for countries to cut down their rainforests. Farmland is made. This is both arable land which is used for tropical crops such as cassava and bananas, and grass land which is used for livestock farming, mainly cattle ranching. This farmland, as well as providing food, gives employment and earns money in export earnings for the country. The wood cut down is sold as timber and used as fuel. Tropical hardwoods are much in demand for use in building and furniture. The main markets for the tropical hardwoods are in the developed world. It will allow the mining of minerals. Many important ores such as bauxite and iron ore have been found in tropical rainforest areas. The most economical way to remove the rocks is often by opencast mining, which means that the trees have to be cut down. The produce power and water supplies. Rivers have been dammed to make large reservoirs for Hydro-Electric Power schemes. An example is the Sobradino Dam on the San Francisco River in Brazil.