The geological structure is a product of periglacial weathering, specifically frost wedging on granite blocks.
The formation is part of a wider collection of boulder fields scattered throughout the Javořice Highlands.
Despite its playful name, the site is a recognized point of interest in the official Czech hiking trail network.
The surrounding landscape is part of the Bohemian-Moravian Highlands, known for its granite bedrock base.
Devil's Ass, known locally as Čertův zadek, is a distinct granite rock formation located in the forested landscape near Kunžak in the South Bohemian region of the Czechia. The site features a large, weathered boulder characterized by a unique cleft that resembles a posterior, giving rise to its colloquial name. It is situated within the Javořice Highlands, an area noted for its glacial-era geological features. The rock is a popular waypoint for hikers traversing the marked trails through the surrounding mixed coniferous forests. The formation is a natural monument rather than an architectural structure, requiring no entry fees or formal access. Access is strictly via unpaved forest paths accessible primarily by foot or mountain bike.
From the front-facing trail perspective to clearly capture the distinct shape of the cleft.
Wear sturdy, waterproof hiking boots as forest paths can be muddy after rain.
Bring a topographic map or GPS device, as mobile signal can be inconsistent in the dense forest.
Mosquito repellent is recommended if visiting during the summer months.
Do not attempt to reach the site by standard passenger car; the forest paths are unpaved and restricted to authorized vehicles.
Accessible year-round, but snow and ice may obscure forest trails in winter.
