John Bonner will present the film, the “Great Unknown” during the Mathews Maritime Foundation’s next speaker meeting, at 7 p.m. next Thursday, Nov. 21, at the MMF Museum, Main Street. The public is invited to attend.

In 1869, the last blank spot on the map of the United States included the canyons of the Colorado River. The film describes how one-armed Major John Wesley Powell journeyed into that area, called the Great Unknown. Bonner will discuss his recent travels in that area. ...