Waves, wind, water and ice shape and reshape the Earth's land surface. Evidence from rocks allows us to understand the evolution of life on Earth. Earth and life history are influenced by occasional catastrophic events, such as the impact of an asteroid or major volcanic eruptions. Unbalanced forces cause changes in velocity. The geology of California underlies the state's wealth of natural resources as well as its natural hazards.
Earth materials are solid rocks and soils, water, and the gases of the atmosphere.
The varied materials have different physical and chemical properties, which make them useful in different ways, for example, as building materials, as sources of fuel, or for growing the plants we use as food. Earth materials provide many of the resources that humans use. Soils have properties of color and texture, capacity to retain water, and ability to support the growth of many kinds of plants, including those in our food supply. The surface of the earth changes. Some changes are due to slow processes, such as erosion and weathering, and some changes are due to rapid processes, such as landslides, volcanic eruptions, and earthquakes.