The diagram illustrates the natural cycle of stone formation, showing how rocks are created, transformed, and recycled through various geological processes.
Overall, the process is cyclical and involves several key stages, including volcanic activity, weathering and erosion, sediment deposition, metamorphism, and melting. Heat, pressure, and surface conditions play essential roles in changing rocks from one type to another.
The cycle begins with magma formation beneath the Earth’s surface, driven by internal heat and tectonic movement. When a volcanic eruption occurs (on average three times per year, as indicated), magma reaches the surface and cools, leading to solidification. This process forms igneous rocks such as granite and basalt.
Over time, these rocks undergo weathering and erosion due to chemical and mechanical causes, particularly during the first several months. The broken pieces are transported mainly by water and wind. These sediments are deposited, especially along river bends, where they accumulate and undergo lithification, forming sedimentary rocks.
With increasing pressure (around 2400 atm) and extremely high temperatures (up to 3200°C), sedimentary rocks transform into metamorphic rocks. Eventually, through subduction and melting, these rocks turn back into magma, completing the continuous natural rock cycle.