Columnar Basalt - South Puyallup Campground

During the cooling of a thick lava flow, contractional joints or fractures form. If a flow cools relatively rapidly, significant contraction forces build up. While a flow can shrink in the vertical dimension without fracturing, it can't easily accommodate shrinking in the horizontal direction unless cracks form; the extensive fracture network that develops results in the formation of columns. The topology of the lateral shapes of these columns can broadly be classed as a random cellular network. These structures are predominantly hexagonal in cross-section, but polygons with three to twelve or more sides can be observed. The size of the columns depends loosely on the rate of cooling; very rapid cooling may result in very small (<1 cm diameter) columns, while slow cooling is more likely to produce large columns.

2016ACTIVITIESAugustColumnar BasaltHikingMount RainierMount Rainier National ParkMt RainierMt Rainier National ParkNational ParkNational Park ServiceNorth AmericaPacific NorthwestParkSouth Puyallup Camp SiteSummerUSAUnited StatesUnited States Department of the InteriorWashingtonWashington StateWonderland Trailrugged