Atigun River in Alaska Brooks Range foothills
View westward along Atigun River in Atigun Gorge. Rocks in foreground are Lower Cretaceous Fortress Mountain Formation. Rocks in gorge, along river, are Lower Cretaceous Okpikruak Formation. Mountains on horizon are mostly carbonates of Carboniferous Lisburne Group. Location in Brooks Range foothills, about 100 miles southeast of Umiat.