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Yellowstone Lake
With a surface area of 132 square miles, Yellowstone Lake is the largest lake at high elevation (i.e., more than 7,000 ft.) in North America. It is a natural lake, situated at 7,733 ft. above sea level. It is roughly 20 miles long and 14 miles wide with 141 miles of shoreline. It is frozen nearly half the year. It freezes in late December or early January and thaws in late May or early June.
Recent research by Dr. Val Klump of the Center for Great Lakes Research and the University of Wisconsin has revolutionized the way we look at Yellowstone Lake. Figuratively, if one could pour all the water out of Yellowstone Lake, what would be found on the bottom is similar to what is found on land in Yellowstone; geysers, hot springs, and deep canyons. With a small submersible robot submarine, the researchers found a canyon just east of Stevenson Island which was 390 ft. deep. Prior to this finding, the deepest spot in the lake was thought to be 320 ft. at West Thumb. Underwater geysers, hot springs, and fumaroles were found at West Thumb and Mary and Sedge bays. The hottest spot in the lake was found at Mary Bay where the temperature was recorded at 252° F (122° C). Hollow pipes, or chimneys of silica, several feet in height, were found rising up from the lake bottom at Mary Bay. It is thought that these are the old plumbing systems of now dormant geysers. Rock spires up to 20-feet tall were found underwater near Bridge Bay. Samples of this rock are being analyzed, though it is believed that these features are probably related to underwater thermal activity.
This group of researchers also found that the conditions in Yellowstone Lake are similar to those that occur near the famous hydrothermal vents on the Pacific Ocean's mid- ocean ridge. Nutrient- and mineral-rich submarine fountains support incredible plant and animal communities, including bacterial mats, sponges, and earthworms.
Yellowstone River
The Yellowstone River is the last major undammed river in the lower 48 states, flowing 671 miles from its source southeast of Yellowstone into the Missouri River and then, eventually, into the Atlantic Ocean. It begins in the Absaroka Mountain Range on Yount Peak. The river enters the park and meanders through the Thorofare region into Yellowstone Lake. It leaves the lake at Fishing Bridge and flows north over LeHardy Rapids and through Hayden Valley. After this peaceful stretch, it crashes over the Upper and Lower falls of the Grand Canyon. It then flows generally northwest, meeting it's largest tributary, the Lamar River, at Tower Junction. It continues through the Black Canyon and leaves the park near Gardiner, Montana. The Yellowstone River continues north and east through the state of Montana and joins the Missouri River near the eastern boundary line of the state. The Missouri River eventually joins the Mississippi River, which flows into the Atlantic Ocean at the Gulf of Mexico.
In addition to the Yellowstone River, many of the spawning streams in the Lake/Fishing Bridge/Bridge Bay area provide critical food sources for grizzly bears in the spring time. Therefore, ecologically speaking, these river and streams are a primary resource in the district. The LeHardy Rapids are a cascade on the Yellowstone River, three miles north of Fishing Bridge. Geomorphologically, it is thought that this is the actual spot where the lake ends and the river continues it's northward flow. In the spring, many cutthroat trout may be seen here, resting in the shallow pools before expending bursts of energy to leap up the rapids on the their way to spawn under Fishing Bridge.
The rapids were named for Paul LeHardy, a civilian topographer with the Jones Expedition in 1873. Jones and a partner started off on a raft with the intent of surveying the river, planning to meet the rest of their party at the Lower Falls. Upon hitting the rapids, the raft capsized, and many of the supplies were lost, including guns, bedding, and food. LeHardy and his partner saved what they could and continued their journey to the falls on foot.
The rapids became a popular visitor attraction when a boardwalk was built in 1984 providing access to the area. Due to increased visitation, a group of harlequin ducks, which once frequented this area in spring, have not been seen for several years. The boardwalk has consequently been closed in early spring to protect this sensitive habitat, but the harlequins have not returned.
Mud Volcano/Sulphur Caldron
When the Washburn Expedition explored the area in 1870, Nathaniel Langford described Mud Volcano as "greatest marvel we have yet met with." Although the Mud Volcano can no longer be heard from a mile away nor does it throw mud from it's massive crater, the area is still eerily intriguing.
The short loop from the parking lot past the Dragon's Mouth and the Mud Volcano is handicapped accessible. The half-mile upper loop trail via Sour Lake and the Black Dragon's Caldron is relatively steep. Two of the most popular features in the Mud Volcano front country are the Dragon's Mouth and the Black Dragon's Caldron. The rhythmic belching of steam and the flashing tongue of water give the Dragon's Mouth Spring it's name, though its activity has decreased notably since December 1994. The Black Dragon's Caldron exploded onto the landscape in 1948, blowing trees out by their roots and covering the surrounding forest with mud. The large roil in one end of the Caldron gives one the sense that the Black Dragon itself might rear it's head at any time.
In January 1995, a new feature on the south bank of Mud Geyser became extremely active. It covers an area of 20 by 8 feet and is comprised of fumaroles, small pools, and frying-pan type features. Much of the hillside to the south and southwest of Mud Geyser is steaming and hissing with a few mudpots intermixed. This increase in activity precipitated a great deal of visitor interest and subsequent illegal entry into the area.
The most dramatic features of the Mud Volcano area however, are not open to the public. The huge seething mud pot known as the "Gumper" is located off-boardwalk behind Sour Lake. The more recent features just south of the Gumper are some of the hottest and most active in the area. Ranger-guided walks are offered to provide visitors an opportunity to view this interesting place.
Farther in the backcountry behind Mud Volcano, several features are being tested for the existence of thermophilic microbes, which may offer insights into origin of life theories as well as having medical/environmental applications.
The Sulphur Caldron area can be viewed from a staging area just north of Mud Volcano. The Sulphur Caldron is among the most acidic springs in the park with a pH of 1.3. Its yellow, turbulent splashing waters bring to mind images of Shakespeare's soothsayers. Other features which can be viewed from this overlook are Turbulent Pool (which is no longer "turbulent") and the crater of a large, active mudpot.
For more specific information on the features of the Mud Volcano/Sulphur Caldron area, consult the annual reports that are available in the Ranger Naturalist Office adjacent to the Fishing Bridge Visitor Center.
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