Upper Geyser Basin stretches in a right triangle from Old Faithful Geyser north and west, mostly along the Firehole River. The hot springs and geysers draw upon the local groundwater for their source of water but also upon deep underground reservoirs. This hydrothermal area contains more than 20 percent of all the geysers in the world, as well as thousands of non-erupting hot springs. T. Scott Bryan, in his book, The Geysers ofYellowstone, writes: To properly experience the Upper Geyser Basin, one should spend at least two or three days to wait for the large and famous geysers to erupt, as well as to enjoy the smaller features.
There are minor details to be observed in the basin, too the colors, wildflowers, forest life, thermophilic communities, and so on many of which are found nowhere else in the world. To spend less time is to cheat oneself. What exactly is a geyser? A geyser is a hot spring that throws forth jets of water and steam intermittently. As you wander through the area, try to guess which seemingly placid hot pools or deep holes may be active geysers, even if they don’t erupt while you’re watching. Here are some telltale signs of active geysers: A deep or wide white crater that does not look cracked and dry Areas downhill from the crater that are devoid of life due to hot water Puddles of water around a crater when it hasn’t been raining Dead but standing trees nearby, indicating a relatively new geyser Concentric rims or formations of the pale brittle rock called geyserite. The Old Faithful interchange bypasses most of the thermal features. Before it was built, the Grand Loop Road ran past many of them, including Morning Glory Pool and Grotto and Castle geysers.
The only current access to these fascinating but sensitive features is by foot or bicycle. Many of the bicyclists you see here are members of an association of geyser enthusiasts (see 361). Vandalism to the geysers and pools has decreased noticeably since the rerouting of trac, but the road relocation has made it dicult for older or disabled visitors or for those with very little time to view such less-accessible marvels as Grand Geyser and Black Sand Pool. It’s some consolation that a wheelchair may be borrowed from the visitor center. Even the hardy should not be surprised if hills that don’t look steep set you to pung and your heart to beating fast it’s the altitude! A few conveniently located benches are especially welcome on the hilly parts of Geyser Hill.