The Mammoth Terraces are constantly changing! You need to approach them closely to appreciate the variety of colors and the heat and power of the springs. Ask at the visitor center where to find the best hot spring activity. There are many steps, but it’s worth the effort and covers a total of about 1 mile (l.6 km). A pamphlet about the terraces is available from the box near the Liberty Cap parking area. NOTE: Upper Terrace Drive has a wheelchair-accessible boardwalk ( 269). Opal Terrace Park at one of the several areas at the foot of the terraces. The easiest terrace to get to is Opal Spring and Terrace, the only formation east of the main road and inactive in the early 21st century. As you approach Opal Terrace, you may wonder why a large and beautiful house would have been built so close to an active terrace. Built in 1908, the house was designed by Robert Reamer for Yellowstone Park Association president Harry W. Child. There was no spring here then, or if there was, it was tiny! Since 1926, Opal Spring deposited a foot or more (about 30 cm) of travertine each year it was active, but it has alternated between dormant and active since 1982.
Nature now usually wins out in disputes over territory, but the National Park Service must also protect the house as a cultural site. The runoff from Opal Spring as Lower Terrace Boardwalk, Part From 1992 to 2008 Lower Hymen Terrace (across Clematis Creek from the bus parking area) was delightfully active, but summer 2008 found it quite dry and white. Next to the stone house here are trailheads for the Beaver Ponds, Howard Eaton, and Sepulcher Mountain trails. Forty-five-foot-high (14 m) Liberty Cap, an extinct hot spring cone, is named for the conical hats given to emancipat-with many of the springs above it flows through underground channels, not on the surface. Tracer dyes were injected down a nearby sinkhole in a recent study. It was found that the hot spring water When it’s active, Opal Terrace threatens to overwhelm Executive House (1996). takes about two hours to reach Boiling River about 1.5 miles (2.5 km) in a straight line below Mammoth. We’ll divide the remainder of the Lower Terrace area above the road into two walks, Parts I and II.