The rock cycle refers to the relationships between igneous, sedimentary and metamorphic rocks and their processes of transformation. Hot magma cools to form igneous rocks, and igneous rocks at the surface are subject to weathering and erosion to form rock fragments. Water and wind carry the debris into rivers, lakes and oceans, where they are deposited to form sedimentary rocks. Igneous and sedimentary rocks are transformed into metamorphic rocks by pressure, heat and fluid effects in the Earth’s crust. Metamorphic rocks exposed at the surface are worn into debris and transported to form new sedimentary rocks. Sedimentary and metamorphic rocks are melted due to heat, stress and fluid effects to form magma, and the magma cools into igneous rocks. This rock cycle is a continuous process, and the concept of the rock cycle is important for understanding the formation of landforms and landscapes.