Mammoth Hot Springs Lower Terraces Trail

The Lower Terraces Trail is a 1.75-mile circuit through the Lower Terraces boardwalk network, starting and ending at the Lower Terraces North Trailhead by Liberty Cap. The route mapped here follows the connected lower boardwalk paths and retraces short spurs where they end, rather than forcing them into a made-up loop. The park describes several access points and ways to explore, not one prescribed lower-only circuit, so this is a north-started option. Allow about 60 to 90 minutes with stops. If you are short on time, the north spur to Palette Spring is about 135 yards one way.

Begin in the parking area in front of Liberty Cap. The paved approach changes to boardwalk, then passes the base of Liberty Cap and reaches Palette Spring about 135 yards from the lot. Liberty Cap is a 37-foot hot-spring cone left by a spring that kept its plumbing open in one place long enough for minerals to build up. The 1871 Hayden Survey named it because its shape reminded the surveyors of the peaked caps associated with the French Revolution. From here, the southbound fork joins the rest of Mammoth's hot-spring trails and boardwalks.

Palette Spring starts on a flat area, then water runs down a steep slope in bands of brown, green, and orange. Heat-tolerant bacteria give the hillside its color. Minerva Terrace, farther along the lower paths, has ornate travertine shapes and bright colors of its own. Its activity has shifted between active and quiet periods since records began in the 1890s. At times, new mineral deposits grew over the old boardwalk. The raised, movable boardwalk now spans the hill as the spring changes again.

The boardwalk network passes through the Main Terrace area, where new springs appear and others go inactive. The terraces are never quite the same from one visit to the next because hot water deposits minerals quickly and its flow shifts around the hillside. From Main Terrace, Mount Everts rises behind the pale shelves. Its sandstone and shale layers formed when this region lay beneath a shallow inland sea, 70 to 140 million years ago.

Mammoth's terraces are made of travertine, a form of calcium carbonate built from limestone. Rain and snow seep into the surrounding mountains, where the water is heated underground. As it moves through limestone, it dissolves calcium carbonate; when the water reaches the surface and releases carbon dioxide, the mineral settles out and builds pale shelves and pools. The fast deposition can reshape a spring and its boardwalk. Scientists have proposed two heat sources, the large magma chamber beneath the Yellowstone Caldera or a smaller source closer to Mammoth, but the answer is still unsettled.

For hundreds of years, Shoshone and Bannock people collected minerals from Mammoth's terraces to make white paint. It's an important part of the place's history and worth keeping in mind as you look across the same pale deposits. The name Liberty Cap also ties the landscape to an early survey: members of the 1871 Hayden party thought the cone looked like a liberty cap.

Stay on boardwalks, designated trails, or roads. The crust around springs can be thin, and the water can cause severe burns. Some sections have steep grades and stairs, so the full circuit is not a wheelchair route; the Palette Spring view is accessible by wheelchair when snow is not on the ground, though the transition from pavement to boardwalk may need assistance. Most boardwalks are not maintained in winter, and snow changes which sections are usable. Pets are not allowed.