“Petroglyphs of the Middle Fork of the American River,” featuring images of petroglyphs recorded by archaeologists working near the American River, is the subject of a presentation by Tahoe National Forest Archaeologist Nolan Smith. The free lecture, presented by Placer County Museums, begins at 1 p.m. Saturday, Oct. 30, on the second floor of the Bernhard Museum Winery, 291 Auburn Folsom Road, in Auburn. Petroglyphs are the patterns of lines and images carved into stone. Unlike pictographs, which are images drawn or painted onto a rock’s surface, petroglyphs are created by removing part of the rock itself. Who created them? Why were they created? What do they mean? Nolan will share his knowledge and insights about petroglyphs during the presentation. For more information, call (530) 889-6500.