Situated in the Owyhee Canyonlands of southeast Oregon and one of the most remote areas of the nation you will find a hidden gem unlike anything else in Oregon, Leslie Gulch. The most striking features of Leslie Gulch are the diverse and often stark, towering and colorful geologic formations.
The Leslie Gulch Tuff (consolidated volcanic ash), makes up the bulk of these formations. It is a rhyolite ash that erupted from the Mahogany Mountain caldera (a large volcanic depression which encompasses Leslie Gulch) in a series of violent explosions about 15.5 million years ago. Much of the material fell back into the volcano as a gaseous deposit of fine ash and rock fragments up to 1,000 feet thick. About 100,000 years later, volcanic eruptions from the Three Fingers caldera, located several miles to the northeast, deposited another layer of rhyolite tuff in Leslie Gulch. Today, the tuff is beautifully displayed as steep slopes and vertical, honeycombed towers carved over time.