Mammoth Hot Springs Lower Terraces

Mammoth Hot Springs’ Lower Terraces are a connected field of pale travertine shelves, pools and spring vents above the Mammoth developed area. Boardwalks pass named features including Liberty Cap, Palette Spring, Minerva Terrace and Canary Spring. Give the larger terrace walk 30 to 90 minutes, depending on which sections you explore; this is one of Yellowstone’s defining stops for close-up geology.

Several access points reach different parts of the terrace system. Boardwalks and paved paths include steep grades and steps; connecting the Lower and Upper Terraces means climbing several hundred stairs. If that climb is too much, use Upper Terrace Drive to reach the upper side. Some boardwalk sections are wheelchair accessible, including the tops of Palette and Canary Springs when the ground is snow-free; transitions from asphalt to boardwalk may need assistance. Most boardwalks are not maintained in winter.

Stay on designated boardwalks, trails and roads: hydrothermal water can severely burn you. Pets are not allowed on the trails.

Palette Spring’s dark Devil’s Thumb stands out against pale mineral steps, while Minerva Terrace gives you a close view of ledges and flowing water. Use the boardwalk as a line into the scene, or frame a nearer terrace edge to show its scalloped layers. The flow and colors change, so the patterns in one photograph may not be there on your next visit.

Trillions of microscopic thermophiles gather in mats that appear as bands of color. The hottest water can look clear or yellow; cooler edges may show orange, brown and green. Look where the water spills over a ledge: the shift from pale mineral deposits to darker living mats makes the temperature differences visible.

Rain and snow seep down from surrounding mountains and are heated underground. As the water rises through limestone, it carries dissolved calcium carbonate. At the surface, carbon dioxide escapes and the mineral is deposited as travertine, building the terraces. The deposition can be rapid, so the shape of the ledges changes over time.

Fractures and fissures carry the hot water to the surface, and small earthquakes may help keep those routes open. Scientists have proposed heat from Yellowstone’s large magma chamber or from a smaller source closer to Mammoth; the explanation is still unsettled.

For hundreds of years, Shoshone and Bannock people collected minerals from the Mammoth terraces to make white paint. Their history here sits alongside the geological story written into the travertine itself.