Rescue excavation is exactly as the name implies – an excavation to rescue the information (including artefacts, environmental remains and plans of structures), in a site which is in danger of being destroyed. Rescue excavations are the most numerous type of excavation in Britain today. Development pressures are a major cause: in a crowded and small country, it is not always possible to build roads, housing estates, motorways, pipelines or airports without affecting archaeology. Other causes include erosion: for instance many of the most interesting archaeological sites are located on cliffs and beaches, and are being damaged by storms and high tides. Archaeologists go in to excavate what is left and save the information they represent.