Mark Walzynski will discuss the historic 1673 expedition of Louis Jolliet and Father Jacques Marquette at 1 p.m. on Saturday, Sept. 20, at the La Salle County Genealogy Guild, 115 W. Glover St., Ottawa.

Jolliet and Marquette were the first Europeans to explore and document what is now Illinois and La Salle County.

The presentation, titled “Jolliet and Marquette’s Epic 1673 Journey,” will highlight the significance of the voyage as a precursor to later explorations in North America.

Walyznski is an author, historian and speaker specializing in the French Canadian and Native American history of the western Great Lakes and Illinois Country. He is affiliated with the Illinois State Archaeological Survey and the Prairie Research Institute in Champaign.

The public is invited to attend. Refreshments will be served, but research materials will not be permitted during the program.