01 February 2010

Goblin Valley is a State Park in Emery County in central Utah, in the western United States. Its eminent feature is its thousands of hoodoos and hoodoo rocks, which are formations of mushroom-shaped rock pinnacles, some as high as several meters. The distinct shape of these rocks comes from an erosion-resistant layer of rock atop softer sandstone.

Vegetation is limited to hardy desert species that can endure blowing sand and hot dry surface conditions. Vegetation and wildlife exist on a limited supply of water in the arid desert environment. Plants have adapted by reducing the size of their leaves to reduce evaporation, with some having a waxy coating on their leaves that reduces water loss. Flora occupying Goblin Valley include Mormon tea (joint fir), Russian thistle, Indian ricegrass, and various cacti. Juniper and pinion pine grow at slightly higher elevations.

Animals often must travel many miles to find water or else wait for thunderstorms to provide moisture. Most animals in the area are nocturnal, venturing out only in the cooler evenings to hunt and forage for food. Some animals get water from the food they eat and go for weeks without a drink of water. Jack rabbits, scorpions, kangaroo rats, pronghorn antelope, kit foxes, midget faded rattlers, lizards, and coyotes are found within and near the park.

The unusual stone shapes in Goblin Valley result from the weathering of Entrada Sandstone. They consist of debris eroded from former highlands and redeposited on a former tidal flat of alternating layers of sandstone, siltstone and shale. The rocks show evidence of being near an ancient sea with 1) the ebb and flow of tides, 2) tidal channels that directed currents back to the sea and 3) coastal sand dunes.

Joint or fracture patterns within the Entrada's sandstone beds created initial zones of weakness. The unweathered joints intersected to form sharp edges and corners with greater surface-area-to-volume ratios than the faces. As a result, the edges weathered more quickly, producing the spherical-shaped 'goblins'. Wiki