Roadside turnout with historic information sign - Photo fronm turnout Gravel turnout, east side of highway. Tribal tradition states that as long ago as the 16th century, the Fall River Valley & canyon area were seldom without groups of Tetis belonging to North American Plains Tribes. They knew the curative value of the warm springs located there and used them for bathing their sick & lame. Exploration of the area in 1874- 1875 led to the discovery of 75 geothermal springs. Nebraska / South Dakota State Line to the Black Hill National Forest Recration Area Black Hills National Forest stretches for 1.2 million acres, offering outdoor adventure like hiking, biking and camping amidst stunning scenery. Find grassy mountain meadows, towering granite peaks, deep canyons, cascading trout streams and clear, clean lakes.