Instruct: Given a question, retrieve relevant passages that can help answer the question.
Query: What is the largest glacier on Mount Rainier?
Emmons Glacier is on the northeast flank of Mount Rainier, in Washington.[2] At 4.3sqmi (11km2), it has the largest surface area of any glacier in the contiguous United States.[3] The glacier was named after the geologist Samuel Franklin Emmons after his involvement in a survey of Mount Rainier in 1870.
The worst mountaineering accident on Mount Rainier occurred in 1981, when eleven people lost their lives in an ice fall on the Ingraham Glacier.
This was the largest number of fatalities on Mount Rainier in a single incident since 32 people were killed in a 1946 plane crash on the South Tahoma Glacier.
About 35,000 years ago, the combined Cowlitz and Ingraham glaciers terminated some from Mount Rainier. As the Ice Age ended the glacier retreated north back to Mount Rainier. In recent times, the glacier has retreated and thinned, except for the period between the mid-1970s and mid-1980s, during which the glacier made a notable advance.
With 26 major glaciers and of permanent snowfields and glaciers, Mount Rainier is the most heavily glaciated peak in the lower 48 states. The summit is topped by two volcanic craters, each more than in diameter, with the larger east crater overlapping the west crater. Geothermal heat from the volcano keeps areas of both crater rims free of snow and ice, and has formed the world's largest volcanic glacier cave network within the ice-filled craters, with nearly of passages.
A small crater lake about in size and deep, the highest in North America with a surface elevation of , occupies the lowest portion of the west crater below more than of ice and is accessible only via the caves.
Flett Glacier refers to two glaciers on the northwestern flank of Mount Rainier in the U.S. state of Washington. The glaciers lie on a subsidiary peak of Rainier, the Observation Rock. There are two sections of glacial ice, an eastern lobe at about to in elevation, a smaller western lobe at about in elevation. Meltwater from the glacier flows into the Puyallup River.
The Wilson Glacier is a medium-sized tributary glacier located on the southeast flank of Mount Rainier in Washington. Named after A.D. Wilson, who was part of an early ascent of Mount Rainier, the body of ice has an area of and has a volume of 1.9 billion feet (54 million m). The glacier is directly feeds ice to the adjacent, but much larger Nisqually Glacier. Starting from the head at , the glacier flows downhill southward. One part of the glacier meets the Nisqually Glacier at and the other part of the glacier ends on a cliff in between the Wilson and Nisqually Glacier at . Meltwater from the glacier feeds the Nisqually River.
Unicorn Peak is the highest point in the Tatoosh Range which is a sub-range of the Cascade Range. It's located in Mount Rainier National Park, south of Mount Rainier. The descriptive name is for the mountain's resemblance to the head and horn of a unicorn. Precipitation runoff from the mountain's small glaciers, such as Unicorn Glacier, drains into tributaries of the Cowlitz River. 
The Nisqually Glacier is one of the larger glaciers on the southwestern face of Mount Rainier in the U.S. state of Washington. The glacier is one of the most easily viewed on the mountain, and is accessible from the Paradise visitor facilities in Mount Rainier National Park. The glacier has had periods of advance and retreat since 1850 when it was much more extensive. It is currently retreating. Measurements made at altitude show that glacier got thicker between 1994 and 1997, suggesting that it will probably begin advancing in the first decade of the 21st century. Nisqually Glacier is the source of the Nisqually River.
Kautz Creek is a tributary of the Nisqually River, flowing from the Kautz Glacier, with its watershed in the Mount Rainier National Park of Washington. It drains southwest from Mount Rainier for about before it joins the Nisqually River near Mount Rainier Highway. It is notable for being a severe flooding hazard due to the volume of summer glacier melt and its frequently changing course. The Kautz Creek Falls on the headwaters of the creek was formed by the retreat of the Kautz Glacier in the past 50 years.
The Liberty Cap Glacier is a small glacier located near the summit of Mount Rainier, Washington. True to its name, the glacier does start at the Liberty Cap above the steep and rocky Sunset Amphitheater and the Mowich Face. Since the topography of Mount Rainier is very jagged and uneven, the glacier is warped and twisted during its descent northward down to its terminus at about . From there, the glacier ice falls off the cliff and tumbles down the steep Mowich Face; eventually, this ice contributes to the large North Mowich Glacier at an elevation of .
The Kautz Glacier is a narrow glacier on the southern flank of Mount Rainier in Washington. Named for August Kautz, who is sometimes credited for the first ascent of Mount Rainier, covers and contains 7.8 billion ft (221 million m) of ice. Upper Kautz Glacier extends south from the summit ice cap to Kautz Ice Cliff at about . Immediately west of the main ice cliff, the glacier continues down Kautz Chute which terminates in another ice cliff just above the lower Kautz Glacier at . Usually reached by a short descent from Camp Hazard at on Wapowety Cleaver, climbers following the Kautz Glacier climbing route ascend this chute to the upper glacier.
The South Mowich Glacier is a glacier located on the western flank of Mount Rainier in Washington. It covers and contains 4.5 billion ft (127 million m) of ice. Starting from the high-altitude cliffs above the Sunset Amphitheater at over , the glacier flows west down Mount Rainier. The glacier is connected to the large Tahoma Glacier to the south near St. Andrews Rock at . After leaving the Amphitheater, there is an icefall on the glacier where it plunges down below . As the glacier descends, it gradually turns and by the time the South Mowich meets the Puyallup Glacier at , the glacier is flowing northwest. As the glacier nears Jeanette Heights, it passes by several turns and becomes very rocky in comparison to the upper sections of the glacier. The glacier splits into two arms before their termini, with a shorter, northern arm ending at and the longer, larger southern arm ending near a stand of conifers at . Meltwater from the glacier drains into the South Mowich River which eventually merges with the Puyallup River.
The Russell Glacier is a medium-sized glacier on the north flank of Mount Rainier, Washington. Named for the geologist Israel Russell, it covers and contains 3.1 billion ft (88 million m) of ice. Starting from its highest point at , the Russell Glacier flows northeast towards the Carbon Glacier and contributes ice to the larger glacier before becoming distinct below . With most of the ice located from to , the glacier only descends to , unlike the much lower extent of the Carbon Glacier. Echo Rock and Observation Rock, two minor sub-peaks of Rainier, lie northwest of this glacier. Meltwater from the glacier eventually reaches the Carbon River.
The Puyallup River begins in two forks, the North Puyallup River and the South Puyallup River. Both originate at glaciers on Mount Rainier. The North Puyallup River flows from the toe of Puyallup Glacier, while the South Puyallup River flows from Tahoma Glacier. The two streams flow through the western part of Mount Rainier National Park, joining just outside the park boundary and forming the Puyallup River proper.
Between the 14th century and 1850, many of the glaciers on Mount Rainier advanced to their farthest extent downvalley since the last ice age. Many advances of this sort occurred worldwide during this time period known to geologists as the Little Ice Age. During the Little Ice Age, the Nisqually Glacier advanced to a position downvalley from the site of the Glacier Bridge, Tahoma and South Tahoma Glaciers merged at the base of Glacier Island, and the terminus of Emmons Glacier reached within of the White River Campground.
The glaciers on Mount Rainier can generate mudflows, through glacial outburst floods not associated with any eruption. The South Tahoma Glacier generated 30 floods in the 1980s and early 1990s, and again in August, 2015.
The size of glaciers on Mount Rainier has fluctuated significantly in the past. For example, during the last ice age, from about 25,000 to about 15,000 years ago, glaciers covered most of the area now within the boundaries of Mount Rainier National Park and extended to the perimeter of the present Puget Sound Basin.
The Van Trump Glacier is actually a scattering of glaciers and snowfields located on the southern flank of Mount Rainier in Washington. Named after P. B. Van Trump, who was part of an early ascent of Mount Rainier, the glacier covers and contains 500 million ft (14 million m) of ice. The glacier is located between the Wilson Glacier to the east and the Kautz Glacier to the west. The elevation of the scattering ranges from at the lower end to on the upper reaches of the glacier. Meltwater from the glacier drains into the Nisqually River.
The Ohanapecosh Glacier is small glacier located on Mount Rainier's southeastern flanks in Washington. It covers and contains 1.3 billion ft (37 million m) of ice. The glacier consists of several lobes of ice interconnected by thin snowfields. Most of the glacier lies at an elevation of to , near the Whitman and the Fryingpan Glacier. Since this ice lobe ends on a cliff, it contributes ice to the lower portions of the Ohanapecosh Glacier. The lower sections of this glacier end on cliffs and a small valley at about in elevation. Meltwater from the glacier drains into the Ohanapecosh River and the Muddy Fork Cowlitz River, which merge downstream about four miles (6 km) outside of Mount Rainier National Park into the Cowlitz River.
Mount Rainier is circled by the Wonderland Trail and is covered by glaciers and snowfields totaling about . Carbon Glacier is the largest glacier by volume in the contiguous United States, while Emmons Glacier is the largest glacier by area. Mount Rainier is a popular peak for mountaineering with some 10,000 attempts per year with approximately 50% making it to the summit.
Mountain climbing on Mount Rainier is difficult, involving traversing the largest glaciers in the U.S. south of Alaska. Most climbers require two to three days to reach the summit, with a success rate of approximately 50%, with weather and physical conditioning of the climbers being the most common reasons for failure. About 8,000 to 13,000 people attempt the climb each year, about 90% via routes from Camp Muir on the southeast flank, and most of the rest ascend Emmons Glacier via Camp Schurman on the northeast. Climbing teams require experience in glacier travel, self-rescue, and wilderness travel. All climbers who plan to climb above the high camps, Camp Muir and Camp Schurman, are required by law to purchase a Mount Rainier Climbing Pass and register for their climb. 
Additionally, solo climbers must fill out a solo climbing request form and receive written permission from the Superintendent before attempting to climb.
Ingraham Glacier is on the south-eastern flank of Mount Rainier, in the U.S. state of Washington. The glacier is named for the Mount Rainier enthusiast Edward Sturgis Ingraham. From the summit ice cap, Ingraham Glacier flows east between Gibraltar Rock, (), and Disappointment Cleaver and south of Little Tahoma Peak (), which divides it from the much larger Emmons Glacier to the north. Descending southeast, it approaches the east flank of Cowlitz Glacier and the two glaciers nearly join at . Meltwater from the glacier drains into the Cowlitz River.
The "Carbon River Entrance Station" is located in the northwest corner of the park off Highway 165 and is the site of the only rainforest at Mount Rainier. There is a campground and a short trail through the rainforest, as well as a trail to the Carbon Glacier, one of the lowest glaciers in the contiguous United States.
The Cowlitz Glacier is on the southeast flank of Mount Rainier in the U.S. state of Washington. The body of ice covers and has a volume of 6 billion ft (170 million m). The glacier starts at an elevation of and flows southeast. An adjacent glacier, the Paradise Glacier, is connected to this glacier on its southwest margin. As it flows down the slopes of Mount Rainier it nearly meets up with the Ingraham Glacier and during the Little Ice Age, which ended around the year 1850, the two glaciers shared a common terminus. Meltwater from the glacier drains into the Cowlitz River.
Pinnacle Glacier is in Mount Rainier National Park in the U.S. state of Washington, on the northeast slopes of Pinnacle Peak. Pinnacle Glacier is south of Mount Rainier and is a small remnant glacier that has developed a proglacial lake as it has retreated.