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|Crater Lake National Park (2)|
The main feature, and the reason for the existence of the national park, is Crater Lake itself. The sight of Crater Lake, "The Gem of the Cascades", is absolutely unforgettable. It is one of the most spectacular sighs on earth and one of America's and the National Park Service's Crown Jewels. The blue of the lake may be unmatched in any body of water anywhere in the world. There are other lakes in the world which have formed in the calderas of volcanoes, but none are quite the same as Crater Lake, and none is so spectacular or so beautiful. Crater Lake is uniquely blue, incredibly deep, and appears so tranquil.
Crater Lake is almost perfectly circular and it is surround by cliffs which rise as much as 2,000 feet above the lake surface. From almost any position on the rim the entire lake can be seen without obstruction, as in the view below looking 6 miles across the lake toward the east rim. The entire caldera is 6 miles wide, 20 miles around, and 4000 feet deep. The lake surface itself lies at an altitude of 6176 feet.
The surface area of the lake is about 20 to 21 square miles. It contains 4 cubic miles of water, which can also be measured as 5 trillion gallons. At its deepest point the lake is 1932 feet deep, making it the deepest lake in the United States. The average depth is 1148 feet. It is also believed to be the 7th deepest lake in the entire world, and the second deepest lake in the western hemisphere. The dropoff to great depth is extreme in places, as for example in one location the lake reaches a depth of 1200 feet only 100 feet from shore.
The lake surface covers nearly 80% of its drainage basin. Almost all of the water which runs into the lake reaches it via rain or snowfall, with about 66 inches a year of precipitation, and 44 feet of snow. There are, however, a number of springs, perhaps 50, which have been found along the wall of the caldera which provide a route for groundwater to flow into the lake. It is estimated that the lake is filled at a rate of 3-4 feet per year. This rise is balanced by water lost though evaporation and through seepage into the porous rock which underlies the lake. Interestingly, a drop of water which enters Crater Lake is expected to remain in the lake itself for 150 years (known as "residence time."
It is, by the way, thought that the level of the lake may have once been 50 feet higher than it is at present. However, since it has been studied scientifically during the last 120 years, the level of the lake has appeared to fluctuate only about 16 feet, with yearly fluctuations typically only around 3-4 feet.
But most striking is the deep blue color, a result of two characteristics of the water. The first is the extreme purity and clarity of the lake, due to a lack of organic material, dissolved minerals, and organic material in the water. It is possible that sunlight penetrates more deeply through the waters of this lake than any on earth. The second characteristic is the lake's depth of the lake, as the deeper the lake the deeper the color of blue. The molecules of water in the lake absorb the colors of sunlight except for blue, which is scattered back to the surface of the lake, resulting in the vivid blue color. The lake is also free of chemicals, sediments, and other materials which cannot be carried into the lake from nonexistent streams and rivers flowing into it.
The clarity of the lake is amazing. On a summer day one can see 40 to 60 feet down through the water. The precise clarity of the lake is measured using a Sechi Disk, a flat, patterned object which is lowered into the water until it can no longer be seen. The record clarity--the depth at which the disk can still be seen-- at Crater Lake is 142 feet. Crater Lake is among the purest bodies of water in the world.
The desire to measure the depth of the lake has been around for a long time. The very first soundings taken of the depth were performed by Clarence Dutton of the USGS in 1886. Along with Mark Kerr and William Steel, Dutton plied the lake in a small boat called The Cleetwood, which Steel had arranged to be built, making soundings of the lake's depth using a piece of pipe attached to a spool of piano wire at 168 locations. At that time, the lake was determined to be 1996 feet deep at its maximum depth, a remarkably accurate figure given the technology employed.
The surface temperature of the lake in the summer ranges from about 55-68 degrees, while the bottom is about 38 degrees. During the winter, the surface temperature of the water falls toward, but seldom below, freezing.
Crater Lake has gone by several names. It has been called "Deep Blue Lake","Blue Lake", and "Lake Majesty", among others, as those providing the names struggled to characterize the incredible site they had witnessed.
Geological History Crater Lake was formed when a 12,000 foot volcano called Mt. Mazama erupted explosively. Prior to 1992 it was thought that this eruption occurred 6850 years ago, but it is now believed to have happened closer to 7700 years before the present. The mountain was named by the Mazama Club, a group of mountaineers organized by William Gladstone Steel in 1894. Mazama itself began to form a little less than 700,000 years ago. About 50,000 years ago the mountain reached its highest altitude of between 11,000 and 12,000 feet, the largest mountain in the general area. The mountain was probably not a classic symmetrical cone, but instead was formed of multiple overlapping volcanoes. Some believe the volcano resembled present day Mt. Rainier.
The cataclysmic eruption of Mt. Mazama was massive--over 42 times as powerful as the one which rocked Mt. St. Helens to the north in 1980. The eruption, or series of eruptions, of Mt. Mazama probably went on for several days. 10 cubic miles of material were ejected during the eruption, and 25 cubic miles were ejected during the complete series of eruption of the volcano. Ash from the eruption reached an altitude of 20-30 miles and covered the earth to a depth of 2 inches as far as 700 miles downwind. 5000 square miles of central Oregon were covered by 6 inches of ash, and parts of present day Oregon, Washington, California, Nevada, Idaho, Montana, British Columbia, and Saskatchewan were blanketed by ash. The eruption injected fine ash high into the stratosphere which was transported all around the planet. Fine material derived from Mt. Mazama has been found in ice cores of Greenland glaciers. Hot ash and pumice flows reached as far as 35 miles from the mountain. The eruption was so great that the material ejected into the atmosphere lowered temperatures in the northern hemisphere several degrees for a few years.
When the material in the magma chamber below the mountain had been emptied the summit collapsed, creating a massive caldera 6 miles wide and 4000 feet deep. Subsequent landslides further widened the caldera. Over time, further volcanic activity created Wizard Island and sealed the caldera floor, although hydrothermal vents were discovered at the bottom of the lake in 1988 and 1989. Wizard Island is not the only volcanic cone built up from the caldera floor, as Merriam Cone (discussed below) also exists. However, volcanic activity at the site has been relatively quiet for 4250 years.
Over time , the caldera filled with water with ground water and through snow or rain. By about 300 years (although some estimates figure this might have taken as long as 700 years) the lake had risen to approximately half of today's level. Eventually, after perhaps about 700-1500 years, a balance was achieved between the water falling into the lake via rain and snow, as well as some springs on the bottom of the lake, and evaporation, resulting in the present level of the lake. The level of the lake lies about 2/3 of the way up the walls of the caldera. There is no river or stream into or out of the lake. The balance between the input by precipitation and ouptut via evaporation and seepage continues, as the level of the lake typically varies less than 3 feet from year to year. Actually, the maximum variation of the level of the lake has been only 16 feet.
Crater Lake is considered oligotrophic; that is, it is characterized by low productivity. This is due to a very short growing season, extraordinary depth, and a basin surrounded by very steep walls.
The lake itself had no native fish. However, William Gladstone Steel actually introduced some fish into the lake in 1888. He later added some shrimp as well. The practice of stocking the lake continued until 1942. To this day some Kokanee salmon and rainbow trout still live in the waters. In 1905, 3 years after the creation and opening of the park, the lake was opened to limited fishing. In 1910 50,000 fry were planted in the lake, along with some brown crayfish. Between 1920 and 1930 the lake was stocked with rainbow and German brown trout. However, in modern times introduction of non-native species into the lake has been discontinued. The last time the lake was stocked with fish was in 1941.
In 1987 a remotely controlled submersible was used to explore the bottom of the lake. An interesting era for the lake occurred in 1988-1989 when a manned, one person submarine was used to explore the bottom of the lake. The 1989 underwater exploration found a number of interesting features below the surface of the lake. Hydrothermal vents on the bottom of the lake and along the caldera wall at a depth of 1500 feet were observed. In other places strange "gardens" of yellow-gold bacteria. A number of other living creatures were also found, including small worms, crustaceans, midge flies, and larvae. Additionally, moss could be found growing between 100 and 460 feet in depth, like icicles hanging from vertical cliffs.
In the year 2000 sophisticated mapping of the bottom of the lake was performed by a research vessel, which established the maximum depth of the lake at 1958 feet.
Interestingly, life has been found even at depths in the lake. At 1932 feet flatworms, nematodes, earthworms, crepapods (???), ostrurods (???), and midge flies have been found. The Deep Rover expeditions actually found some light penetrated all the way to the bottom of the lake.
The two things which strike the visitor when the lake is first encountered is just how blue the water is, and how enormous the lake appears as it stretches out beneath the walls of the caldera.
The first photograph of Crater Lake was taken by Peter Britt of Jacksonville, Oregon, in 1874. Britt had to spend time at the rim waiting out bad weather, but eventually got 7 glass plate negatives. His photograph of the almost unbelievable caldera and lake was in no small part responsible for making Crater Lake a statewide attraction and a national landmark.
In more modern times, at least 3 films have been shot in the area--Sundown, in 1941, Canyon Passage in 1946, and in 1980 an IMAX program on the eruption of Mt. St Helens.
Wizard Island is not the only volcanic cone which has grown from the bottom of the caldera, although it is the only one visible above the surface of the lake. Merriam Cone is probably the last of the andesite volcanoes which grew after the caldera was created. It's summit rises about 1450 feet above the floor of the lake's east basin, rising to within 500 feet of the surface of the lake. In all probability all of its volcanic components were ejected beneath the surface of the water.
The most amazing perspective of the lake is from its surface. Fortunately for visitors to Crate Lake National Park, there is a boat trip available which carries people all over the surface of the lake. This boat, loaded with visitors, is shown below.
Boat tours of Crater Lake have been going on for a long time. Tours of the lake by boat first began of in 1907. The boat on the surface of the lake provides some of the most spectacular views of the lake. The boat below is seen in the vicinity of The Phantom Ship. This feature appears surprisingly large when viewed from the lake surface.
The only place to reach the lake's surface from the rim of the Caldera is in Cleetwood Cove. The Cove is reached by a very steep trail with a number of switchback. A view of the cove from this trail is shown in the picture below.
The dock lies at the end of the trail and is shown below.
Another perspective of Cleetwood Cove is shown below. The lowest section of Cleetwood Trail can be seen as it approaches the boat dock.
The boat trip takes visitors all over the surface of the lake and provides them with close up views of many of the features of the caldera rim. Below, the wake of the boat tracing its route toward the dock at Cleetwood Cover can easily be seen.
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