| Nisqually Glacier | |
| Type: | Mountain glacier |
| Coords: | 46.8347°N -121.7464°W |
| Area: | 1.8sqmi in 1983 |
| Length: | 4miles |
| Terminus: | moraine |
| Status: | Retreating [1] |
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.[1] Measurements made at altitude show that glacier got 56feet thicker between 1994 and 1997, suggesting that it will probably begin advancing in the first decade of the 21st century.[2] Nisqually Glacier is the source of the Nisqually River.[1]
Perhaps the longest studied glacier on Mount Rainier, Nisqually's terminal point has been measured annually since 1918.[3] In May 1970, the glacier was measured to be moving at an average of per day.[4]
Nisqually Glacier has advanced and retreated three times during the end of the 20th Century. The recent retreat began in 1985. In the next six years, the glacier thinned by 52feet west of Glacier Vista.[5]
The glacier reached its greatest extent by 1850, when many of the glaciers reached their furthest extent down valley. The 1850s is considered the Little Ice Age. Nisqually Glacier reached 650feetto800feetft (toft) feet below the Glacier Bridge. On the west, Tahoma and South Tahoma Glaciers joined below Glacier Island along the Wonderland Trail. Emmons Glacier on the northeast reached within 1.2mile of the White River Campground.[5]
With the end of the Little Ice Age these glaciers began a slow retreat. After 1920 the rate of shrinkage sped up. In the 100 years since the height of the Little Ice Age and 1950, Mount Rainier lost about one-quarter its glaciers. After 1950 until the 1980s the larger glaciers made small advances. Since the 1980s, many glaciers have been thinning and retreating.[5]
The glacier is one of four on Mount Rainier that are known to have released debris flows. Similar flows have stemmed from the Winthrop, Kautz, and South Tahoma glaciers as well.[1]