Mt. Mazama began its most destructive eruption about 7,680 years ago. A distinct band of volcanic chemicals and ash particles was discovered in the Greenland ice in a layer dated to 7,676 years ago. A caldera formed by the collapsing of the top of the mountain, during the catastrophic eruption of almost 50 cubic kilometers of magma. Twenty feet of ash accumulated at the base of Mt. Mazama. Ash deposits sprayed over the entire region as far away as Alberta, Canada to the north; Nevada and Northern California to the south; and as for as Yellowstone National Park in Wyoming to the east. The tremendous explosion of ash was followed by a series of large glowing avalanches. The whole mountain was set a blaze as trees and plants were incinerated. One fiery avalanche traveled 40 miles down the Rogue River Valley. After the eruptions ended, the air was full of choking, volcanic dust. Heavy rains fell and clouds of steam and fine dust billowed upward. When the air cleared, the summit was gone, but the canyons remained hot and smoking for years. Only a great pit, a caldera, was left. It was five miles wide and 4,000 feet deep. Approximately 15 to 17 cubic miles of the mountaintop had exploded and collapsed. More astonishing is that nearly three times as much new rock was spewed out of the volcano’s insides, as the volume of old rock that had made up the summit. Still, the activity was not over. Minor activity continued deep in the caldera. Another volcano formed inside this massive pit called Wizard Island. It rises almost 800 feet above the lake. Rain and snow accumulated and gradually filled the pit. Crater Lake is the deepest lake in the United States. At 1,932 feet deep, this beautiful lake has no inlet or outlet and is known for its intense blue color. Two other cones have formed on the crater’s floor, but remain submerged.
For more from the references USGS or Volcano.und.Nodak.edu Mount Mazama, Mt. Mazama, Mt Mazama, Mazama, Crater Lake, Oregon.