Audio
Lassen Audio Tour Stop 14 - Chaos Crags Vista
Transcript
Stop 14. Chaos Crags Vista The stark domes of jagged rock before you are the aptly named Chaos Crags. These are lava domes, like Lassen Peak, and are some of the youngest volcanoes in this part of the park. Imagine being here 1,100 years ago and watching them slowly rise out of the ground. It would be an awesome sight as pasty lava oozed upward, accompanied by explosions of steam. The massive eruptions formed six lava domes which sat quietly steaming for centuries. Then, 700 years ago, one of the domes collapsed creating a violent high-speed rock avalanche that raced across what is now the park highway and part way up Table Mountain to your north. The rockfall dammed Manzanita Creek, forming Manzanita Lake. Since then, a dwarf forest has grown over the waves of broken rock. Their stunted size is a testimony to their resilience as they slowly reclaim the Chaos Jumbles.
This jumbled landscape is evidence of the unstable nature of lava domes. In the 1970s, two scientists became concerned about the potential for future landslides in the Manzanita Lake area. To ensure visitor safety, the park closed its Manzanita Lake facilities. In the following decades, additional research helped scientists determine that while rockfall hazards were possible, it was unlikely that a future avalanche would reach the developed area.
Scientists have been monitoring this area since the dramatic eruption of Lassen Peak in 1915. You can see the first seismic station in the stone building adjacent to the Loomis Museum. Today, staff at the Cascade Volcano Observatory watch for indicators of increased volcanic activity. Stop by the Loomis Museum or go online to view a real-time map of seismicity in the park. Scientists in Menlo Park, California are using the same information to monitor the earthquakes that continuously rock this region and remind us that this is indeed a restless land.
Description
700 years ago, one of the five lava domes that comprise Chaos Crags collapsed. This created a violent high-speed rock avalanche that raced across what is now the park highway and part way up Table Mountain to the north.
Credit
NPS
Date Created
09/01/2018
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