The Yellowstone River is the longest free-flowing river in the lower 48 states, and for 103 miles downstream from Gardiner it is designated a Blue Ribbon trout stream, the longest single stretch of Blue Ribbon water in Montana, drawing anglers to a nationally renowned cold-water fishery for brown, rainbow, and native Yellowstone cutthroat trout in what is known as Paradise Valley. Few valleys in the Rocky Mountains match the Yellowstone's variety of landforms, shaped by glaciers, landslides, volcanic activity, and great folds and faults, with visible evidence all along the river. The Yellowstone Ice Sheet flowed northward from the Yellowstone Plateau at least twice, and where this area now lies the glacier was once more than 3,000 feet thick, depositing rocks and sediment in Paradise Valley and shaping the surrounding mountains; at the north end of Yankee Jim Canyon, a roche moutonnee on the west side of the river shows how glacier ice scraped and polished bedrock. Volcanic forces also helped form many of the mountains here, leaving deposits of volcanic rock such as andesite and basalt cliffs, signs of a petrified forest in Tom Miner Basin caused by ancient volcanic ash and mudflows, and the continuing geothermal reminder of La Duke Hot Springs, where water from 135 to 149 degrees Fahrenheit flows from the east bank of the Yellowstone River. From Gardiner through Yankee Jim Canyon, four rapids can be extremely dangerous, especially during high water, usually in June. Long before the present, people lived and worked along the Yellowstone River five thousand years ago; archaeologists identify them as part of the archaic culture, which prospered for about 1000 years. In summer they followed bison, antelope, and mountain sheep into the mountains, while also hunting smaller game and gathering plants and seeds, and in fall they returned to the valley, sustained by its rich resources.