Mineral exploitation directly affects organisms through both physical and chemical modification of their environment, and indirectly in a variety of ways. Excavation alters landform, drainage and soil conditions, while waste disposal has parallel effects and, along with processing, may cause pollution problems elsewhere. The effects on nature conservation interest vary according to the type and quality of habitat, vegetation and animal communities concerned, but mineral extraction can create new habitats of considerable value as well as causing damage. Adverse effects include direct habitat destruction, e. g. quarrying of important limestone areas and mining of ironstone; and production of chemical conditions unfavourable to both terrestrial and aquatic plants and animals, e. g. lead mining in Wales. Benefits are mainly the creation of new or more varied habitats, including lakes and marshes (flooded gravel pits and salt-mine subsidence); cliffs, screes and waste ground (quarries and mine tips); and old access routes, walls and buildings. Lead-mine spoil has greatly increased the populations of certain local plant species. In the past the gains to nature conservation interest have probably outweighed the losses, but the future scale and methods of mineral extraction may pose more serious problems, as through opencast working for ball clay and copper, removal of important coastal shingle beaches, and final exhaustion of the Magnesian limestone. Conservation in the broadest sense requires that ecological knowledge be employed to restore all derelict land to productive use, but this should include nature conservation as well as other uses such as agriculture. Nature conservationists have the knowledge to advise where mineral extraction would cause serious damage, and to indicate how operations elsewhere might be conducted with advantage to their interests. It is, however, important that their information and views be made as early as possible in the planning process controlling future extraction.