Lava is molten rock that flows onto the Earth's surface, representing the visible phase of magmatic activity. This material originates from magma, which is found deep beneath the crust, and is released through volcanic vents or fissures. The physical properties of the lava, including its temperature, viscosity, and chemical composition, dictate the manner in which it travels and solidifies. Highly fluid, low-viscosity lavas tend to flow over vast distances, creating shield structures, while more viscous lavas tend to pile up, resulting in steep-sided formations. The rapid cooling and eventual solidification of lava flow material contribute to the formation of igneous bedrock and defining geological landforms.