Coulées

Coulées are a geological term referring to a flow of lava. They are a type of volcanic eruption where molten rock moves across the Earth's surface. The viscosity of the lava greatly influences the speed and distance a coulee can travel. Thinner, less viscous lavas tend to flow more readily, creating long, relatively flat coulees. Thicker, more viscous lavas move more slowly and can build up into more massive formations. These flows can vary significantly in size, from small streams of lava to vast expanses that cover hundreds of square kilometers. The surface of a coulee can cool and solidify into different textures depending on the lava composition and cooling rate, often forming rough, jagged surfaces or smoother, ropy patterns. Over time, vegetation may colonize coulees, and they can become important habitats. Geologists study coulees to understand volcanic processes and the history of volcanic activity in a region. Many ancient coulees are visible features in landscapes shaped by past volcanic events.