| Yellowstone Lake |
|
on a fall morning
|
| Location |
Yellowstone National Park, Wyoming, U.S. |
| Coordinates |
44°28′00
N°110′22Coordinates: 44°28′00
N°110′22 |
| Primary outflows |
Yellowstone River |
| Basin countries |
USA |
| Max length |
20 mi (32 km) |
| Max width |
15 mi (24 km) |
| Surface area |
136 sq mi (352 km²) |
| Average depth |
139 ft (42 m) |
| Max depth |
390 ft (118 m) |
| Shore length1 |
110 mi (177 km) |
| Surface elevation |
7,732 ft (2,376 m) |
| Islands |
6 |
|
1 Shore length is not a well-defined measure. |
Yellowstone Lake is the largest body of water in Yellowstone National
Park, The lake is 7,732 feet (2,376 m) above sea level and covers 136 square miles (352 km²) with 110 miles (177 km) of
shoreline. While the average depth of the lake is 139 feet (42 m) its deepest spot is at least 390 feet (118 m). Yellowstone Lake
is the largest freshwater lake above 7,000 feet in North America.[1]
In winter, ice nearly 3 feet (1 m) thick covers much of the lake, except where shallow water covers hot springs. The lake
freezes over by early December and can remain frozen until late May or early June.
Geology
Yellowstone Lake from space.
In the southwest area of the lake the West Thumb geothermal area is easily accessible to visitors. Geysers, fumaroles and hot springs are
found alongside and even in the lake. See Geothermal areas of
Yellowstone.
In recent years (as of 2004), the ground under the lake has started to rise significantly,
indicating increased geological activity, and limited areas of the national park have been closed to the public. As of
2005, no areas are currently off limits aside from those normally allowing limited access such as
around the West Thumb Geyser Basin. There is a 'bulge' about 2,000 feet (600m) long and 100 feet (30m) high under a section of
Yellowstone Lake, where there are a variety of faults, hot springs and small craters. Seismic imaging has recently shown that
sediment layers are tilted, but how old this feature is has not yet been established.
The famous Yellowstone Lake Hotel as seen from Yellowstone Lake
After the magma chamber under the Yellowstone area collapsed 600,000 years ago in its
previous great eruption, it formed a large caldera that was later partially filled by subsequent
lava flows (see Yellowstone Caldera). Part of this
caldera is the 136 square mile (352 km²) basin of Yellowstone Lake. The original lake was 200 ft. (60m) higher than the
present-day lake, extending northward across Hayden Valley to the base of Mt. Washburn.
It is thought that Yellowstone Lake originally drained south into the Pacific Ocean via
the Snake River. The lake currently drains north from its only outlet, the Yellowstone River, at Fishing Bridge. The elevation of the lake's north end does not drop
substantially until LeHardy Rapids. Therefore, this spot is considered the actual northern boundary of Yellowstone Lake. Within a
short distance downstream the Yellowstone River plunges first over the upper and then the lower falls and races north through the Grand Canyon
of the Yellowstone.
A rainbow hangs over Yellowstone Lake.
In the 1990s, geological research has determined that the two volcanic vents, now known as
"resurgent domes", are rising again. From year to year, they either rise or fall, with an
average net uplift of about one inch per year. During the period between 1923 and 1985, the Sour Creek Dome was rising. In the years since 1986, it has either declined
or remained the same. The resurgence of the Sour Creek dome, just north of Fishing Bridge is causing Yellowstone Lake to "tilt"
southward. Larger sandy beaches can now be found on the north shore of the lake, and flooded areas can be found in the southern
arms.
The Hayden Valley was once filled by an arm of Yellowstone Lake. Therefore, it contains fine-grained lake sediments that are now covered with glacial till left from the most
recent glacial retreat 13,000 years ago. Because the glacial till contains many different grain
sizes, including clay and a thin layer of lake sediments, water cannot percolate readily into the ground. This is why the Hayden
Valley is marshy and has little encroachment of trees.
References cited
External link
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