The development of a community may be influenced by many geological phenomena, for example, earthquakes (Chapter 1), weathering and erosion (Chapter 3), volcanoes (Chapter 5), landslides and avalanches of rock and soil (Chapter 14). To these obstacles may also be added the problems of engineering with the materials and landscape created by geological processes, for example, the difficulty of creating reservoirs (Chapter 15), and of excavating routes for communications (Chapter 14 and 16). These, and other examples, are mentioned in previous Chapters, as indicated.