April 7, 2023 3:30 a.m.

Roseburg Public Library will host a presentation about the volcanic formation of Crater Lake at 4:00 p.m. Thursday April 27th.

Presenter Larry Broeker was a geologist for the Umpqua National Forest from 1990 to 2008. He will discuss the process in which the ancestral Mt. Mazama filled with magma and then erupted, resulting in the six-mile wide caldera which is known as Crater Lake.

Broeker said some 7,700 years ago, a batch of doughy magma that had been brewing beneath Mt. Mazama for nearly 30,000 years burst forth in a deafening blast. An immense cauliflower-shaped column of dark, gritty ash and frothy bits of pumice soared upward from a solitary vent into the stratosphere and rode the prevailing currents as far as the Canadian province of Alberta.

Broeker will go in-depth about the momentous eruption which radically altered the physical appearance and ecology of the landscape.

The 90-minute program will be in the library’s Deer Creek Room and is free and open to the public. For more information, call the library staff at 492-7050 or email: library@cityofroseburg.org