+Trabzon+(Turkey).jpg)
Visiting glaciers is surely one of the highlights of a journey to Alaska. There are an estimated 100,000 glaciers in the State, covering three percent of the landscape and creating most of its rivers. Glaciers are rivers of ice that flow from ice packs high in the mountains, where more snow falls than melts. In constant motion, they can move ahead at speeds of several feet a day, or sudden surges of as much as 300 feet. Some are retreating, or shrinking due to increased melting or a lack of new snow to feed them.
Tidewater glaciers flow to the sea and are found at the head of fjords or inlets which they carved while retreating. Calving occurs when pieces of a tidewater glacier break off and fall into the sea. The creaking sounds associated with calving glaciers and the roar as pieces fall into the sea are as impressive as the visual scene. The beautiful blue color associated with glaciers is created by the density of the ice which absorbs all the colors of the spectrum except blue, which is reflected.College Fjord
College Fjord is a fjord located in the northern sector of Prince William Sound in the U.S. state of Alaska. The fjord contains five tidewater glaciers (glaciers that terminate in water), five large valley glaciers, and dozens of smaller glaciers.
In the summer of 1899, railroad magnate Edward H. Harriman, president of the Union Pacific Railroad and the Washington Academy of Sciences upon advise from his physician to take a sea voyage as an antidote to stress, funded a scientific expedition along the Alaskan coast. The two-month expedition, intended initially as a family vacation, eventually gathered an illustrious group of scientists, naturalists, writers, and artists, and combined scientific research with leisure activities.
It was the Harriman Expedition party who named College Fjord as well as the glaciers that line it. The dozen or so glaciers lining this fjord were named for the Ivy League schools that members of the party attended. On the northwest side of the fjord, the glaciers were named after the women's colleges, such as Smith, Bryn Mawr, Vassar, Wellesley, Barnard, and Holyoke. On the southeast side, the glaciers are named after men's colleges Harvard, Yale, Amherst, and Dartmouth. According to Bruce Molina, author of Alaska's Glaciers, "they took great delight in ignoring Princeton".
Some of these glaciers have retreated since the original Harriman Expedition, but not the largest of them: Harvard. Harvard is 1 1/2 miles wide, approximately 225 feet high at its terminal face, stretches below the waterline up to about 120 feet, and reaches back to the Chugach Icefield nearly 24 miles away. This giant of College fjord is slowly advancing, calving literally tons of ice into the fjord each day. These glaciers parade down, some of them 3,700 feet to the mile, from the steep mountains. No place else is there such a density of tidal glaciers.
There are often harbor seals hauled out on the ice floes in front of Harvard glacier throughout the summer. It’s also not unusual to see large rafts of sea otters together, grooming their luxuriously dense fur, slipping beneath the surface to dine on crab, or simply floating with their babies nestled on their chests watching with curiosity as you pass by.
In 1964 College Fjord was the epicenter of the Good Friday Earthquake, the most powerful earthquake in U.S. history. It is a popular destination for cruise ships. From one place, it is possible to see eight of College Fjords Glaciers at once.
Hubbard Glacier is a tidewater glacier in the U.S. state of Alaska and the Yukon Territory of Canada. From its source in the Yukon, the glacier stretches 122 km (76 mi) to the sea at Yakutat Bay and Disenchantment Bay. Named in 1890 after Gardiner G. Hubbard (regent of the Smithsonian Institution and first president of the National Geographic Society), it is the longest tidewater glacier in Alaska, with an open calving face over ten kilometers (6 mi) wide.
The longest source for Hubbard Glacier originates 122 kilometres (76 mi) from its snout located approximately 8 kilometres (5.0 mi) west of Mt. Walsh with an altitude around 11,000 feet. A shorter tributary glacier begins at the easternmost summit on the Mt. Logan ridge at about 18,300 feet.
Before it reaches the sea, Hubbard is joined by the Valerie Glacier to the west, which, through forward surges of its own ice, has contributed to the advance of the ice flow that experts believe will eventually dam the Russell Fiord from Disenchantment Bay waters.
The Hubbard Glacier ice margin has continued to advance for about a century. In May 1986, the Hubbard Glacier surged forward, blocking the outlet of Russell Fiord and creating "Russell Lake." All that summer the new lake filled with runoff; its water level rose 25 meters, and the decrease in salinity threatened its sea life.
Around midnight on October 8 the dam began to give way. In the next 24 hours an estimated 5.3 cubic kilometres (1.3 cu mi) of water gushed through the gap, and the fiord was reconnected to the ocean at its previous level. This was the second largest glacial lake outburst flood (GLOF) in recorded history.
In spring 2002, the glacier again approached Gilbert Point. It pushed a terminal moraine ahead of its face and closed the opening again in July. On August 14, the terminal moraine was washed away after rains had raised the water level behind the dam it formed to 18 m (61 ft) above sea level. The fiord could become dammed again, and perhaps permanently. If this happens, the fiord could overflow its southern banks and drain through the Situk River instead, threatening trout habitat and a local airport.
It takes about 400 years for ice to traverse the length of the glacier, meaning that the ice at the foot of the glacier is about 400 years old. The glacier routinely calves off icebergs the size of a ten-story building. Where the glacier meets the shore, most of the ice is below the waterline, and newly calved icebergs can shoot up quite dramatically, so that ships must keep their distance from it as they ply their way up and down the coast.
Mendenhall Glacier is a glacier about 12 miles (19 km) long located in Mendenhall Valley, about 12 miles (19 km) from downtown Juneau in the southeast area of the U.S. state of Alaska.
Originally known as Sitaantaagu ("the Glacier Behind the Town") or Aak'wtaaksit ("the Glacier Behind the Little Lake") by the Tlingits, the glacier was named Auke (Auk) Glacier by naturalist John Muir for the Tlingit Auk Kwaan (or Aak'w Kwaan) band 1888. In 1899 it was renamed in honor of Thomas Corwin Mendenhall. It extends from the Juneau Icefield, its source, to Mendenhall Lake and ultimately the Mendenhall River.
The Juneau Icefield Research Program has monitored the outlet glaciers of the Juneau Icefield since 1942 , including Mendenhall Glacier. From 1951–1958 the terminus of the glacier, which flows into suburban Juneau, has retreated 1,900 feet (580 m). The glacier has also receded 1.75 miles (2.82 km) since 1958, when Mendenhall Lake was created, and over 2.5 miles (4.0 km) since 1500. The end of the glacier currently has limited crevassing a negative glacier mass balance and will continue to retreat in the foreseeable future.
Given that average yearly temperatures are currently increasing, and the outlook is for this trend to continue, it is actually possible that the glacier might experience a period of stabilization or slight advance during its retreating march. This is because increasing amounts of warm, moist air will be carried up to the head of the icefield, where colder ambient temperatures will cause it to precipitate as snow. The increased amount of snow will feed the icefield, possibly enough to offset the continually increasing melting experienced at the glacier's terminus. However, this interesting phenomenon will fade away if temperatures continue to climb, since the head of the glacier will no longer have cold enough ambient temperatures to cause snow to precipitate.
Visitor Center
The United States Forest Service administers the Mendenhall Glacier Visitor Center as part of Tongass National Forest. Forest interpreters offer conservation education programs throughout the year for children and adults. It is the only visitor center in the United States within a half mile of a terminal glacier that calves icebergs into a lake. The center is open year-round and receives close to 500,000 visitors each year, many coming by cruise ship in summer.
This was the first US Forest Service visitor center built in the nation. Dedicated in 1963, it originally served pie and coffee in the area of the center that today shows movies to local residents and visitors. Exhibits in the Center cover the history of Mendenhall Glacier showing how it covered the valley when Captain Vancouver toured the area in the late 1770s and what is happening due to climate change today. The exhibits depict the variety of wildlife in the area including mountain goats, wolves, black bears and red salmon in the nearby streams. Forest interpreters provide tours, children's nature programs, point out wildlife and answer questions about the area.
There is a large parking lot with access to several trails in the area. Elevated boardwalks above Steep Creek provide safe bear viewing in August and September. Visitors can hike to a viewing platform within a quarter mile of the glacier. For the more adventurous, there is the Nugget Falls trail that leads you to the 5 story waterfall near the face of the glacier, or you can actually hike up onto the glacier via the West Glacier Trail. Access to the area and trails is free. There is a small fee to go into the visitor center. This fee provides for maintenance of the trails, programs during summer and updating the exhibits in the center.
In addition to the busy summer season, the Center hosts the Fireside program series for several months in winter every Friday night. Programs cover the ecological and culture history and events in Southeast Alaska. Inside the Visitor Center is a natural and cultural history bookstore run by the Alaska Natural History Association which is a non-profit organization supporting the public lands of Alaska. Trail guides, wildlife and bird guides, children books and other materials are available here.
Tracy Arm is a fjord inAlaska near Juneau. It isnamed after a Civil War general named Benjamin Franklin Tracy. It is located about 45 miles (72 km) south of Juneau and 70 miles north of Petersburg, Alaska, off of Holkham Bay and adjacent to Stephen's Passage within the Tongass National Forest. Tracy Arm-Fords Terror Wilderness was designated as a wilderness area by the United States Congress in 1980.
The Tracy Arm area covers 653,179 acres (2,643.32 km2) and consists of two deep and narrow fjords: Tracy Arm and Endicott Arm. Both fjords are over 30 miles (48 km) long and one-fifth of their area is covered in ice. During the summer, the fjord has considerable floating ice ranging from the size of a three-story building to hand-size pieces. During the most recent glaciated period, this fjord filled with active glaciers.
The most common access is by boat using Stephen's Passage and entering Holkham Bay and Tracy and Endicott Arms. Float planes from Juneau and Petersburg are also used as a means of access. Large tour vessels and smaller commercial cruise boats frequently use Tracy Arm as a tour destination or as a stop along their normal tour routes.
Sawyer Glacier
The twin Sawyer Glaciers, North Sawyer and South Sawyer, are located at the end of Tracy Arm. The wildlife in the area includes black and brown bears, deer, wolves, harbor seals, and a variety of birds, such as arctic terns and pigeon guillemots. The mountain goats, which are usually found in the higher elevation areas, have been seen near the base of Sawyer Glacier.
Credit by : http://www.cruiseandtouralaska.com/glaciers.htm
No comments:
Post a Comment