Lassen Peak

Lassen Peak and Devastated Area from Cinder Cone from

The Lassen Peak in California is the largest lava dome volcano ( also known as plug dome) of the earth and the southernmost volcano in the Cascade Range. He is also known as Mount Lassen. It was created on the destroyed northeastern flank of Mount Tehama, a stratovolcano, which was at least 300 meters higher than the omission. Let located in the northern Shasta County in Central California in the Shasta Cascade region and is the center of Lassen Volcanic National Park.

He is the only volcano in the Cascade Range except for Mount St. Helens, which was active during the 20th century. This phase of eruptive activity lasted from 1914 until 1917.

Unlike most volcanoes, lava dome of the type of leave of craters is crowned. There are a number of craters near the summit of which, however, two are covered by massive lava.

Geology

About 27,000 years ago, a dacite lava dome - pressed by the northeast edge of the Tehama up. In this way, overlying rock layers were broken and deposited as talus around the emerging volcano. The Lassen Peak reached its present height in a relatively short time, probably in a few years. In the Ice Age, it was partially eroded by glaciers.

History

Before the arrival of white settlers, the area around the Lassen Peak, particularly in the east and south, the tribal region of the northeastern Maidu.

Lassen Peak was named after the Danish blacksmith Peter Lassen, who led around 1830 settlers from the east to the Sacramento Valley. His route was not long, however used, as it was considered unsafe. The Nobles Emigrant Trail, named after William Nobles, the Nevada joined the Applegate Trail to the northern Sacramento Valley, replaced him.

In 1864, Helen Tanner Brodt boarded the first woman to summit of Lassen Peak. At reminds the name of a Karsees from leaving.

From 1914 to 1921 Have been active with steam explosions, dacite lava flows and lahars. There were between 200 to 400 eruptions during this time, but demanded no deaths or serious injuries.

On May 5, 1915 dacitic lava flowed 300 meters down the western slope before it froze. Observers who were 30 kilometers describes this process as the " boiling mountain". The heat of the lava melted the snow cover and destroyed the deep crater lake at the summit. The resulting lahar flooded the Lost Creek and Hat Creek.

On May 22, at 16:30 local time clock was followed by a massive explosion that caused a mushroom-shaped ash cloud. A pyroclastic flow destroyed and burned trees on the northwest slope and triggered another lahar from. These events formed the so-called Devastated Area, which is still almost treeless because the soil is poor in nutrients and very porous.

In April, May and June 1917, a further series of steam and ash explosions that produced a fourth summit crater ( in the northwest) occurred.

Since that time, the USGS monitored in cooperation with the United States Park Service to Allow and its surroundings.

Swell

• Geology of National Parks: Fifth Edition, Ann G. Harris, Esther Tuttle, Sherwood D., Tuttle (Iowa, Kendall / Hunt Publishing, 1997) ISBN 0-7872-5353-7