The Castle Trail is the longest maintained trail in Badlands National Park, stretching nearly 5.4 miles along the north edge of the Badland Wall. It joins the Medicine Root Trail to form a diverse 8 mile loop through vast prairie and spectacular badland formations.

The Ogalala Sioux called this corner of South Dakota 'mako sica', which means 'land bad'

The Brule Formation is comprised of ash blown in from volcanoes to the west

Native Audubon Bighorn Sheep disappeared in the early 1900s; Rocky Mountain Bighorn Sheep were introduced in 1964

The lighter-colored Sharps Formation was deposited 28-30M years ago as the climate grew dry and cool

Oligocene fossil remains include camels, three-toed horses, rhinoceroses and beaver

Despite relatively mild terrain, fog can make navigation of the badland maze impossible

Ostensibly desolate, over 400 plant and grass species are found in Badlands National Park

Yellow Mounds are an example paleosol, or fossil soil

Western wheatgrass is the predominant grass in the mixed-grass prairies of the Badlands

The Chadron Formation is made of sediments carried in by rivers across a flood plain

The Saddle Pass Trail branches off the Castle Trail with excellent views back up the Badland Wall

Looking south from Saddle Pass across the Buffalo Gap National Grassland

The Castle Trail is marked by tall metal posts to assist navigation through vast open spaces

The Badlands' mixed grass prairies support pronghorn, buffalo, mule deer and badger

The tan-brown Brule Formation was deposited 30-34M years ago as drier climates favored open savannah