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BOBBY SOCKS TREES

Much of the soil within the Yellowstone Caldera is the product of hardened lava flows from the region’s volcanic past and is unsuitable for many types of trees.

The central part of the park is characterized by miles upon miles of lodgepole pine, a tree which thrives in the slightly acidic soil of the caldera. The roots of lodgepole pine extend sideways rather than deep into the ground—an advantage in the caldera where the topsoil is very thin and contains few nutrients.

Dead lodgepole pines near some hydrothermal areas look as if they are wearing white anklet socks, at one time called “bobby socks.” The dead trees soak up the mineral-laden water. When the water evaporates, the minerals are left behind, turning the lower portion of the trees white.

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