Before starting, check at the Norris Museum for info on current geyser predictions. Head through the museum, pass Campground Trail (on right) Back Basin Trail (on left), and head down the hill. Continue straight at the next junction (on left, our trail's return route).
Norris is the hottest, most changing thermal area in Yellowstone. White colored mineral deposits in the basin inspired the name Porcelain Basin. Siliceous sinter is brought to the surface by hot water and forms a "sheet" over this flat area as the water flows across the ground and the mineral settles out. Siliceous sinter is an important agent of change. If it seals off a hot spring by accumulating in its vent, the hot, pressurized water may flow underground to another weak area and blow out.
Going down the hill, observe the thermal area on the left. Most days you see and hear Black Growler. The hottest of Yellowstone's geothermal features are steam vents, or fumaroles. Black Growler’s super-heated steam measures 199 to 280 degrees F. A plentiful water supply would cool these features; but, steam vents are usually found on higher ground, above the water supply. They rapidly boil away the limited water, forcefully releasing steam. If you are extremely lucky you may also see an eruption of Ledge Geyser. It is capable of shooting water 125 feet into the air. Because it erupts at an angle, the water sometimes reaches the ground 220 feet away.
Continue straight at the junction and follow the boardwalk out across the basin. Soon you reach Whirligig and Little Whirligig geysers. Whirligig was so named because its water swirls in its crater during eruptions. The orange-yellow iron oxide deposits around Little Whirligig make it one of the most colorful features in Porcelain Basin.
Amazingly, living organisms thrive even in the extreme environments of these hot acidic springs! The overflow channels of geysers and hot springs are often brightly colored with minerals and microscopic life forms. Hardy lime-green Cyanidium algae thrive in these waters. Orange cyanobacteria is also found in the runoff streams.
The trail bends left through trees. Emerging, you pass Whale's Mouth, named by park naturalists because its shape "resembles the mouth and gullet of a giant fish." A peculiar thing for a trained naturalist to say, since whales are not fish. Next up is Crackling Lake, named for popping sounds from springs on its southern shore. The trail continues up the hill and returns to the museum.
Thanks to guidebook author, Tom Carter, for sharing this trail description. To learn more about visiting Yellowstone, check out his book, Day Hiking Yellowstone