Mammoth Hot Springs - Yellowstone National Park

Main Terrace

You can view this large terrace and its colorful springs from several vantage points. To your left, follow the boardwalk to an overlook of New Blue Spring. One of the best examples of the area's dynamic character, New Blue Spring shifts activity frequently and can become active or inactive several times in one year.

An overlook leads to a view of the entire Main Terrace; at the far right you can see Canary Spring. At the beginning of the trail to Canary Spring, a short spur trail takes you to a view of Cupid Spring, which has resumed activity recently. Continue on the trail to benches where you can relax and watch the waters and colors of Main Terrace. (This platform is also wheelchair-accessible, see map.)

You will likely find flowing hot water, new travertine formations, and shade as you walk alongside Canary Spring. Imagine you were here in the late 1800s, a time when yellow filamentous bacteria was prominent. Today, the spring exhibits the orange, brown, and green seen in other hot springs of the area. See the map for the location of the wheelchair-accessible trail to this site.

From the parking area, look south to Highland Terrace, which recently resumed activity.

Temperature 160°F This spring is part of the Main Terrace, which includes Blue, Jupiter, Naiad and Main springs. All the springs have had intermittent activity, but Canary has been the most regular spring in the group. The name Canary was in reference to the yellow filamentous algae growing along the edge of the spring, and may have been named by the 1904 Hague Expedition. But now Canary Spring is known for its ultramarine-colored pool. The water flowing down the face of the terrace has created multi-colored bands of algae and cyanobacteria.

This spring was active next to the road in the mid-1990s. In the mid-2000s, activity shifted toward the trees. And it may have shifted again by the time you visit.

Tree skeletons stand as monuments to a landscape created in the 1950s. This area has been inactive since the 1980s. Perhaps future visitors will see New Highland rejuvenated.

Temperature 160°F The Highland Terrace area received its name from A.C. Peale, geologist for the 1872 Hayden Expedition. There are many springs and pools in the Highland Terrace area. Most have intermittent activity. New Highland Spring began its activity during the early 1950s. Before that time it was a grassy, wooded hillside. The Spring rapidly formed a massive deposit of porous travertine. Trees on the hillside became engulfed by travertine and now stand as skeletons. Like other thermal features at Mammoth Terraces, New Highland Spring changes from season to season depending on water flow and temperature.

This spring flows from several vents from its top and side. Its striking colors come from the thermophiles living in the hot water.

Temperature 157°F Mound dimensions 48x20 feet. Orange cyanobacteria which streak the large travertine mound are the origin of the name. The spring from this mound is cooler than other thermal features at Mammoth Terraces which allows orange-colored cyanobacteria to dominate. The brilliant color changes from season to season depending on the flow rate and the amount of available sunlight. The mound appears as a large cone-shaped hot spring, but it actually formed along a fracture line of a fissure ridge. Several cones have formed along this line of fracture, including Tangerine Spring. Based on the low flow and deposition from this spring and the size of the mound this formation may be very old.

Bath Lake was a popular swimming hole until it dried up in 1926. It filled again after the 1959 Hebgen Lake Earthquake and remained a lake through the 1970s. By then bathing in hydrothermal features was illegal because it destroys fragile formations and changes their activity.

Water laden with calcium carbonate has flowed from a fissure to build this ridge, which an early tour guide thought resembled the back of an elephant. Activity constantly shifts here.

The dramatic presence of this feature comes from abundant water, white formations, and colorful thermophiles that thrive in hot water. Angel Terrace was dry and crumbling for decades, but resumed activity in 1985. Some of the other dormant features you have seen on this drive may one day flow again too.

Look for this terrace across the road from the main trails—it plays an unusual role in Mammoth. In 1926, Opal began depositing up to one foot (0.3 m) of travertine per year. Its periodic growth threatens the historic house next door, which was designed by Robert Reamer and built in 1908 as an example of Frank Lloyd Wright's Prairie Style architecture. The National Park Service strives to protect both historic and natural resources—a challenge here.

Temperature 160°F When this feature received its name in 1871 by the Hayden Expedition, it was a small spring with opal colors. it was dormant for several years until 1926 when it began to flow again. Since then it has intermittent activity. During the 1940s Opal was very active and rapidly deposited porous travertine, doubling its size. Nearly a foot of travertine deposited a year. The terraces began encroaching on a tennis court and at first the deposits were rerouted. By 1947 the tennis court was removed and the terrace now covers the original site. Opal is still known for its pastel colors, but like most Mammoth Terrace features it constantly changes activity, shape and color.

Across the road from Opal Terrace stands the 37-foot (11 m) Liberty Cap, which was created by a hot spring that was active in one location for a long time. Its internal pressure was sufficient to raise the water to a great height, allowing mineral deposits to build slowly and continuously for perhaps hundreds of years.

Liberty Cap was named in 1871 by the Hayden Survey because it resembled the peaked knit caps symbolizing freedom and liberty during the French Revolution.


Expedition for its resemblance to the caps worn by colonial patriots in the Revolutionary War. The cone formed from a steady flow of hot water emerging from a single source, depositing dense layers of travertine. The cone continued to grow as long as there was a source of water. Either the hot water spring found a more convenient underground channel to escape through or the orifice became sealed by travertine deposits. It is now an inactive spring and it is not known when Liberty Cap became extinct. The weathered outer surface now supports a plant community of lichens, grass and even a small tree.

Water flows in crisscrossing patterns down a steep ridge where colorful thermophiles create a changing palette dominated by hues of orange and brown. This effect is much the same as an artist would achieve by allowing watercolors to run down a vertical surface.

Activity shifts dramatically around this terrace. The cascades of travertine beside the boardwalks were formed in the 1990s. Some years, they are dry. Whatever its level of activity, you can see why Minerva Terrace was named for the Roman goddess of artists and sculptors. Its ornate travertine formations create the look of layer cakes and lace-edged pools. In the dry areas, you can clearly see the many layers and the varying depths.

Minerva Spring is a favorite not only because of its wide range of bright colors but also for its ornate travertine formations. Since the 1890s, when records were first kept on the activity of Mammoth Hot Springs, Minerva has gone through both active and inactive periods. For several years in the early 1900s, it was completely dry, but by 1951 reports state that Minerva was again active.

During some cycles of activity, water discharge and mineral deposition have been so great that boardwalks have been buried beneath mounds of newly deposited travertine. Consequently, an elevated and movable boardwalk now spans the hill in the vicinity of Minerva. In recent years, hot spring activity has shifted dramatically from Minerva to other features on the Lower Terraces, and back again.

Temperature 161°F This spring and terrace is considered one of the most colorful and ornate terraces at Mammoth. Minerva has had periods of inactivity throughout its recorded history, but when it is active terraces of porous travertine form rapidly. During the building of a single terrace, orterracette, travertine precipitates around the edge of a small pool, and can accumulate at a rate of as much as 8.5 inches a year. As the water cascades from terrace to terrace the water cools, allowing algae to grow. Blue-green algae and cyanobacteria, in colors of green, yellow, orange and red, line the terrace run-off channels.

Due to confusion related to the intermittent nature of many of the springs in the Mammoth Area, the name Cleopatra Spring has been given to at least three different springs over the years. As the confusion developed the original Cleopatra Spring came to be called Minerva Spring

These terraces display cycles of activity typical of Mammoth Hot Springs. In 1937, Mound Terrace was called "the most beautifully colored spring." Inactive for decades, its weathered travertine shows new patterns where chunks of the soft rock have broken or fallen. Recently, Mound Terrace began flowing again.

Jupiter Terrace displays cycles of activity. In the 1980s Jupiter Terrace flowed so heavily that it overtook boardwalks several times. It has been dry since 1992, but when active, its color and intricate terraces make Jupiter an appealing spring.