|
Chaos Crags is the youngest group of lava domes in Lassen Volcanic National Park, California, having been formed as five dacite domes 1,100-1,000 years ago. The cluster of domes is located north of Lassen Peak. From the base of the crags and extending toward the northwest corner of the park is Chaos Jumbles, a cold rock avalanche which undermined Chaos Crags' northwest slope 300 years ago.〔 〕 Riding on a cushion of compressed air (see sturzstrom), the rock debris traveled at about , flattened the forest before it, and dammed Manzanita Creek, forming Manzanita Lake. In 1974 the National Park Service took the advice of the USGS and closed the visitor center and accommodations at Manzanita Lake. The USGS stated that these buildings would be in the way of a rockslide from Chaos Crags if an earthquake or volcanic eruption occurred in the area. In 2011, twenty prefab cabins were reinstalled in the Manzanita Lake Campground. It had been determined in the 1980s that the rockslide danger had been overstated by the USGS, and therefore, the cabins were reintroduced to the park for nightly rental.〔http://www.redding.com/news/lassen-park-brings-back-manzanita-lake-cabins〕 == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Chaos Crags」の詳細全文を読む スポンサード リンク
|