Pic Description: Rocks on Earth can be divided into three types: sedimentary rocks (Sedimentary rocks), igneous rocks (Igneous rocks) and metamorphic rocks (Metamorphic rocks). Among them, the formation of sedimentary rock is this: 1. Material accumulation. Low-lying at the earth's surface, such as valleys and basins, deltas, ocean bottom, there will be accumulation of substances (including water and wind transport of these substances to the sand, dirt, dust, biological debris, and originally living creatures here debris). Layers of these substances accumulate year after year, more and more thick, or even to a few kilometers thick. 2. Sediments buried. At the same time, the crust below the sediments are constantly Movement. If this local subsidence, these sediments will be buried deep in the crust, in the enormous pressure, high temperature, through a very long time, and finally the formation of rocks. 3. Sedimentary rock outcrops. These sedimentary rocks have been formed, they might rise due to crustal movement, exposing the surface to form what we see, has a layered structure of the rock. For example, the Yongding River Valley on both sides of the mountain, mostly by the ancient sedimentary rock formed during the composition.
