Hells Canyon National Recreation Area was shaped over millions of years by fire and water, as molten lava erupted from volcanoes and oozed through cracks in the earth, while rushing water, erosion, and sedimentation built up and wore down the land amid folding, faulting, and tremendous pressures beneath the earth’s crust. These geologic forces remain active, with small earthquakes in recent decades reminding us that the earth is still restless, and with movement along faults, rockfalls and landslides, intense storms and melting snow, water cascading into the Snake River from tributary streams, and fluctuating water levels in the canyon continuing to shape the landscape. The Snake River rapids are constantly changing obstacles that require adventurous runners to read the changing faces of both water and rock.