August 28, 2025 3:20 a.m.

Roseburg Public Library invites the public to a presentation on Oregon’s Table Rocks presented by geologist Larry Broeker at 6:30 p.m. on Thursday, September 11th.

A city release said Broeker retired from the Umpqua National Forest and speaks regularly about the iconic landforms of southern Oregon and northern California.

Broeker says about 7 million years ago, a massive outpouring of runny lava swept down the ancestral canyon of the Rogue River 44 miles from source fissures thought to be buried beneath Olson Mountain, an extinct High Cascades shield volcano located a few miles east-southeast of Lost Creek Lake.

Broeker said the lava spread across the northern part of the Rogue Valley and solidified to a depth varying between 100 and 200 feet. Over the past seven millennia, tectonic forces and geologic processes have imperceptibly transformed the Rogue Valley into the present-day horseshoe-shaped landforms of Table Rocks.

The free program will be held at the library on Northeast Diamond Lake Boulevard and is open to the public. For more information contact the library at 492-7050 or email: library@roseburgor.gov