Retired geologist Mark Prchal will discuss Southern Oregon geology from 12:30 to 1:30 p.m. Saturday, July 7, at the Applegate library, 18484 N. Applegate Road.

Retired geologist Mark Prchal will discuss Southern Oregon geology from 12:30 to 1:30 p.m. Saturday, July 7, at the Applegate library, 18484 N. Applegate Road.

Prchal will discuss the origins of Table Rock, Crater Lake, Mount Ashland and Grayback Mountain.

Call 541-846-7346 or see www.jcls.org for more information.