Yellowstone is truly a land of fire and ice. In the very middle of Yellowstone National Park, a large chamber of molten hot magma sits so close to the surface of the earth that it heats the entire Yellowstone Plateau and provides heat for the geothermal features that are part of the wonder and awe of Yellowstone. It is so large that it went unnoticed for over a hundred years. This dynamic "hot spot" expands and contracts and, in so doing, raises and lowers the region by measurable amounts each year. Over geologic time, it has erupted multiple times and the last eruption left behind a volcanic caldera about 20 x 30 miles in size. It will probably erupt again in the near geologic future.
Between eruptions of this super volcano, the landscape was covered by the ice of many glaciers through time. The landforms of volcanism have been modified by these glaciations, and the glaciers and their outwash have determined the drainage patterns of the major rivers within the park. The geology of Yellowstone is a study in the dynamic forces of nature; the current landscape is just the most recent chapter in a book whose pages are being turned daily.
The simple essence of Yellowstone is captured in its many hot springs, geysers, steam vents, and mud pots. While you will find these steaming features throughout the park, the geyser basins have concentrations of them and are well worth a walk around their boardwalks. Each geyser basin and each feature in them is unique. Along the Firehole River alone, are enough geothermal wonders to capture your attention for at least a week! Geyser basins along the Firehole River include:
- Upper Geyser Basin - The home of Old Faithful Geyser, Beehive Geyser, Grand Geyser, and many others! You can spend an entire day in this basin alone.
- Black Sand Basin - A short walk near beautiful Iron Spring Creek will lead you to several large, colorful hot springs.
- Biscuit Basin - Named for biscuit-like geyser deposits that have since been shaken loose by the 1959 Hebgen Lake Earthquake, this basin includes several smaller geysers and beautiful pools.
- Midway Geyser Basin - With the largest hot spring in the park, Grand Prismatic Spring, this basin is very popular. We recommend visiting early or late in the day.
- Lower Geyser Basin - The well-known Fountain Paint Pots are here along with several large geysers and many smaller ones. Take a side trip down Firehole Lake Drive to see if you can catch Great Fountain or White Dome Geysers.
If you are looking for a longer walk and an other-worldly experience, Norris Geyser Basin is for you. Norris's Back Basin is home to the tallest, active geyser in the world - Steamboat Geyser! The Porcelain Basin is full of colorful springs and a few unpredictable geysers as well. Norris is the hottest, most active basin in the park - perhaps because it sits atop three different fault lines!
For a gorgeous view of Yellowstone Lake, stop and walk around at West Thumb Geyser Basin. You can peer into the depths of Abyss Pool and Black Pool, watch the lake water splash around Fishing Cone, and even see some mud pots in this basin. Do watch out for elk and bison as they are frequent visitors to this basin.
Flowing up through limestone, the terraced springs at Mammoth Hot Springs are different from features found in the geyser basins. You won't find any geysers here but this colorful hillside is well worth the walk. You can also drive the Upper Terrace Drive for a less strenuous view of similar features.