According to COCC geologist, Bob Reynolds, the story of the Dry Canyon begins around 3.5 millions years ago with lava flows that formed the rim rock now visible from the Maple Avenue bridge.
Until about 400,000 years ago, the Deschutes River flowed to the east of both Bend and Redmond, merging with the Crooked River near the site of Smith Rock State Park. Around that time, lava flowed from the Newberry Volcano filling the river channel from Bend to Smith Rock and forcing the river west into a new channel in the present day Dry Canyon. The Canyon was carved over the next 300,000 years,
About 78,000 years ago another eruption entered the river channel south of Bend and flowed to the area around present day Yew Avenue in Redmond. Once again the Deschutes was forced west leaving behind the Dry Canyon.
A final (for the time being) Newberry eruption occurred about 75,000 years ago sending lava into and partially filling the Dry Canyon. The lava rubble from this eruption forms the current floor of the Dry Canyon.