LITIA DARMAWATI

Name : Litia Darmawati

Class: D.4.1

Student’s Number : 12.23.030

Lake Tahoe

Lake Tahoe  is a large freshwater lake in the Sierra Nevada of the United States. At a surface elevation of 6,225 ft (1,897 m), it is located along the border between California and Nevada, west of Carson City. Lake Tahoe is the largestalpine lake in North America. Its depth is 1,645 ft (501 m), making it the second-deepest in the United States (the deepest is Crater Lake in Oregon at 1,945 ft (593 m), 300 ft (91 m) deeper). Additionally, Lake Tahoe is listed as the 27th largest lake by volume in the world at 122,160,280 acre·ft (150,682,490 dam³).

The lake was formed about 2 million years ago and is a part of the Lake Tahoe Basin with the modern lake being shaped during theice ages. It is known for the clarity of its water and the panorama of surrounding mountains on all sides.^[6] The area surrounding the lake is also referred to as Lake Tahoe, or simply Tahoe. More than 75% of the lake's watershed is national forest land, comprising the Lake Tahoe Basin Management Unit of the United States Forest Service.

Lake Tahoe is a major tourist attraction in both Nevada and California. It is home to a number of ski resorts, summer outdoor recreation, and tourist attractions. Snow and skiing are a significant part of the area's economy and reputation. Mountain and lake scenery are attractions throughout the year. The Nevada side also includes large casinos. Highways provide year-round access from Reno, Carson City, and Sacramento.

The Lake Tahoe Basin was formed by vertical motion (normal) faulting. Uplifted blocks created the Carson Range on the east and the Sierra Nevada on the west. Down-dropped blocks (grabens) created the Lake Tahoe Basin in between. This kind of faulting is characteristic of the geology of the adjoining Great Basin to the east.

Lake Tahoe is the youngest of several extensional basins of the Walker Lane deformation zone that accommodates nearly 12 mm/yr of dextral shear between the Sierra Nevada-Great Valley Block and North America.

Three principal faults form the Lake Tahoe basin: the West Tahoe Fault, aligned between Emerald Bay and Tahoe City, and which is the local segment of the Sierra Nevada Fault, extending on shore north and south of these localities; the East Tahoe Fault, aligned along the eastern shoreline; and the North Tahoe Fault, which runs between the two others deep under the northern part of the lake. The West Tahoe Fault appears to be the most active and potentially hazardous fault in the basin. A study in Fallen Leaf Lake, just south of Lake Tahoe, used seafloor mapping techniques to image evidence for paleoearthquakes on the West Tahoe and revealed the last earthquake occurred between 4,100 and 4,500 years ago.

Some of the highest peaks of the Lake Tahoe Basin that formed during the process of Lake Tahoe creation are Freel Peak at 10,891 feet (3,320 m), Monument Peak at 10,067 feet (3,068 m), Dicks Peak at 9,974 feet (3,040 m) (in the Desolation Wilderness), and Mount Tallac at 9,735 feet (2,967 m). The north shore boasts three peaks at 10,000+ feet: Mount Rose, Houghton and Relay peaks. Mt. Rose is a very popular hiking and backcountry skiing destination.

Eruptions from the extinct volcano Mount Pluto formed a dam on the north side. Melting snow filled the southern and lowest part of the basin to form the ancestral Lake Tahoe. Rain and runoff added additional water.

Modern Lake Tahoe was shaped and landscaped by scouring glaciers during the Ice Ages, which began a million or more years ago.

Soils of the basin come primarily from andesitic volcanic rocks and granodiorite, with minor areas of metamorphic rock. Some of the valley bottoms and lower hill slopes are mantled with glacial moraines, or glacial outwash material derived from the parent rock. Sandy soils, rock outcrops and rubble and stony colluvium account for over 70% of the land area in the basin. The basin soils (in the < 2 mm fraction) are generally 65-85% sand (0.05–2.0 mm).

Given the great depth of Lake Tahoe, and the locations of the normal faults within the deepest portions of the lake, modeling suggests that earthquakes on these faults can triggertsunamis. Wave heights of these tsunamis are predicted to be on the order of 10 to 33 ft (3 to 10 m) in height, capable of traversing the lake in just a few minutes. A massive collapse of the western edge of the basin that formed McKinney Bay around 50,000 years ago is thought to have generated a tsunami/seiche wave with a height approaching 330 ft (100 m).

Vegetation in the basin is dominated by a mixed conifer forest of Jeffrey pine (Pinus jeffreyi), lodgepole pine (P. contorta), white fir (Abies concolor), and red fir (A. magnifica). The basin also contains significant areas of wet meadows and riparian areas, dry meadows, brush fields (with Arctostaphylos and Ceanothus) and rock outcrop areas, especially at higher elevations. Ceanothus is capable of fixing nitrogen, but mountain alder (Alnus tenuifolia), which grows along many of the basin’s streams, springs and seeps, fixes far greater quantities, and contributes measurably to nitrate-N concentrations in some small streams. The beaches of Lake Tahoe are the only known habitat for the rare Lake Tahoe yellowcress(Rorippa subumbellata), a plant which grows in the wet sand between low- and high-water marks.

Each autumn, from late September through mid-October, mature kokanee salmon (Oncorhyncus nerka), transform from silver-blue color to a fiery vermilion, and run up Taylor Creek, near South Lake Tahoe. As spawning season approaches the fish acquire a humpback and protuberant jaw.After spawning they die and their carcasses provide a feast for gatherings of mink (Neovison vison), bears (Ursus americanus), and Bald eagles(Haliaeetus leucocephalus). These salmon were transplanted from the North Pacific to Lake Tahoe in 1944.

North American Beaver (Castor canadensis) were re-introduced to the Tahoe Basin by the California Department of Fish and Wildlife and the U.S. Forest Service between 1934 and 1949. Descended from no more than nine individuals, 1987 beaver populations on the upper and lower Truckee River had reached a density of 0.72 colonies (3.5 beavers) per kilometer. At the present time beaver have been seen in Tahoe Keys, Taylor Creek, Meeks Creek at Meeks Bay on the western shore, and King's Beach on the north shore, so the descendants of the original nine beavers have apparently migrated around most of Lake Tahoe. Recently novel physical evidence has demonstrated that beaver were native to the Sierra until at least the mid-nineteenth century, via radiocarbon dating of buried beaver dam wood uncovered by deep channel incision in theFeather River watershed. That report was supported by a summary of indirect evidence of beaver including reliable observer accounts of beaver in multiple watersheds from the northern to the southern Sierra Nevada, including its eastern slope. A recent study of Taylor Creek showed that beaver dam removal decreased wetland habitat, increased stream flow, and increased total phosphorus pollutants entering Lake Tahoe - all factors which negatively impact the clarity of the lake's water.^[31] In addition, beaver dams located in Ward Creek, located on the west shore of Lake Tahoe, were also shown to decrease nutrients and sediments traveling downstream.

The lake's cold temperatures and extreme depth can slow the decomposition rate of organic matter. For example, a lost diver was found 17 years later at 300 feet, and his body had been preserved nearly perfectly.

 Visitors can reach Lake Tahoe under ideal conditions within two hours from the Sacramento area, one hour from Reno or thirty minutes from Carson City. In winter months, chains or snow tires are often necessary to reach Tahoe from any direction. Traffic can be heavy on weekends due to tourists if not also from weather.

The primary routes to Lake Tahoe are on Interstate 80 via Truckee, U.S. Highway 50, and Nevada Highway 431 via Reno. Most of the highways accessing and encircling Lake Tahoe are paved two-lane mountain roads. US 50 is a four-lane highway (from the canyon of the South Fork American River at Riverton, over the Sierra Nevada at Echo Summit, and into the Lake Tahoe Basin, is a mainly two-lane road) passing south of the lake and along part of the eastern shore.

California Highway 89 follows the western shore of the lake through the picturesque wilderness and connects camping, fishing and hiking locations such as those at Emerald Bay State Park, DL Bliss State Park and Camp Richardson. Farther along are communities such asMeeks Bay and Tahoe City. Finally, the highway turns away from the lake and heads northwest toward Truckee.

California Highway 28 completes the circuit from Tahoe City around the northern shore to communities such as Kings Beach, Crystal Bay, and into Incline Village, Nevada where the road becomes Nevada Highway 28. Highway 28 returns along the eastern shore to US 50 near Spooner Lake.

Carstensz Pyramid

Puncak Jaya or Carstensz Pyramid (4,884 m) is the highest summit of Mount Carstensz in the Sudirman Range of the western central highlands of Papua Province, Indonesia (within Puncak Jaya Regency). Other summits are East Carstensz Peak (4,808 m), Sumantri (4,870 m) and Ngga Pulu (4,863 m). Other names include Nemangkawi in the Amungkal language, Carstensz Toppen and Gunung Sukarno.

At 4,884 metres (16,024 ft) above sea level, Puncak Jaya is the highest mountain in Indonesia, the highest on the island of New Guinea (which comprises the Indonesian West Papua region plus Papua New Guinea), the highest of Oceania (Australian continent), and the 5th highest mountain in political Southeast Asia. It is also the highest point between the Himalayas and theAndes, and the highest island peak in the world. Some sources claim Mount Wilhelm, 4,509 m (14,793 ft), as the highest mountain peak in Oceania, on account of Indonesia being part of Asia (Southeast Asia). The massive, open Grasberg mine is within 4 kilometers from Puncak Jaya.

The highlands surrounding the peak were inhabited before European contact, and the peak was known as Nemangkawi inAmungkal. Puncak Jaya was named "Carstensz Pyramid" after Dutch explorer Jan Carstenszoon who first sighted the glaciers on the peak of the mountain on a rare clear day in 1623. The sighting went unverified for over two centuries, and Carstensz was ridiculed in Europe when he said he had seen snow near the equator.

The snowfield of Puncak Jaya was reached as early as 1909 by a Dutch explorer, Hendrik Albert Lorentz with six of his indigenous Dayak Kenyah porters recruited from the Apo Kayan in Borneo. The predecessor of the Lorentz National Park, which encompasses the Carstensz Range, was established in 1919 following the report of this expedition.

While Puncak Jaya’s peak is free of ice, there are several glaciers on its slopes, including the Carstensz Glacier, West Northwall Firn, East Northwall Firn and the recently vanished Meren Glacier in the Meren Valley (meren is Dutch for "lakes").^[11] Being equatorial, there is little variation in the mean temperature during the year (around 0.5°C) and the glaciers fluctuate on a seasonal basis only slightly. However, analysis of the extent of these rare equatorial glaciers from historical records show significant retreat since the 1850s, around the time of the Little Ice Age Maximum which primarily affected the Northern Hemisphere, indicating a regional warming of around 0.6°C per century between 1850 and 1972.

                                                                                     

The glacier on Puncak Trikora in the Maoke Mountains disappeared completely some time between 1939 and 1962. Since the 1970s, evidence from satellite imagery indicates the Puncak Jaya glaciers have been retreating rapidly. The Meren Glacier melted away sometime between 1994 and 2000. An expedition led by paleoclimatologist Lonnie Thompson in 2010 found that the glaciers are disappearing at a rate of seven metres thickness per year and should be vanished by 2015.

Puncak Jaya is one of the more demanding climbs in one version of the Seven Summits peak-bagging list. (It is replaced by Mount Kosciuszko in the other version.) It is held to have the highest technical rating, though not the greatest physical demands of that list's ascents. The standard route is up the north face and along the summit ridge, which is all hard rock surface. Despite the large mine, the area is highly inaccessible to hikers and the general public. The "standard" route to access the peak as of 2013 is to fly into the nearest major town with an airport, Timika, and then take a small aircraft over the mountain range and onto an unimproved runway at one of the local villages far down from the peak. It is then typically a 5-day hike to the base camp through very dense jungle and with regular rainfall, making the approach probably the "most miserable" of the Seven Summits. The one-day summit bid can be cold, with patches of snow on the route and ice sometimes appearing on the ropes of the Tyrolean traverse near the summit. The descent from the peak base camp can take three to four days.