Mount Rainier is a massive stratovolcano located in the Cascade Range in the state of Washington. It is composed of many layers of hardened lava, ash, and rock that erupted from a central vent. Over time, the layers accumulated and compressed under their own weight and the pressure of the surrounding rocks. This process of mountain building, called orogeny, caused the rocks to deform, break and uplift the land to form Mount Rainier. Type of terrain and climate also played a part in its formation. Glaciers and rivers eroded the surrounding land, and elevated the mountaintop by carving deep valleys, creating cirques and arêtes, and reshaping the landscape. Rainier was further enlarged by the eruption of melted glacial ice, ash flows, and lava flows from several small, overlapping volcanoes.