NORTHERN SECTION - Yellowstone Treasures - page 305

The runoff from Opal Spring—as with many of the springs above it— flows through un-
derground channels, not on the surface. By injecting tracer dyes down a nearby sinkhole,
scientists found that the hot-spring water reaches Boiling River in about two hours, flowing
about 1.5 miles (2.5 km) below Mammoth.
When it's active, Opal Terrace threatens to overwhelm Executive House (1996).
We'll divide the remainder of the Lower Terrace area above the road into two walks, Parts
I and II .
Lower Terrace Boardwalk, Part I
From 1992 to 2008 Lower Hymen Terrace (across Clematis Creek from the bus parking area)
was delightfully active, but quite dry and white from 2008 to 2012. Next to the stone house
here are trailheads for the Beaver Ponds, Howard Eaton, and Sepulcher Mountain Trails. Fol-
lowing the Howard Eaton Trail a short distance south after crossing the Clematis Creek bridge
leads to Narrow Gauge Terrace, described on page 272 .
Liberty Cap, 1871, by W. H. Jackson