Monkeyface Rock Formation is a geological wonder in Terrebonne, Oregon. It's a basaltic rock formation that forms a huge rock wall with a distinct profile that evokes a monkey's face. The rock formation was formed by lava flows from Newberry Volcano about 650,000 years ago. The face itself is about 55 feet tall, and the entire formation is about 230 feet long. Monkeyface Rock Formation is a popular spot for rock climbers and hikers. The 2.5 mile loop to the summit of Monkeyface Rock offers great views of the surrounding area. There is a picnic area and an interpretive trail in the area, which is open year round.