Within the Lake Clark region itself there are four active (and three of the tallest) volcanoes. Mount Spurr, at 11,070 feet, lies just north of the park. Mount Redoubt, at 10,197 feet, and Mount Iliamna, at 10,016 feet, are both located in the park. To the south of the park lies Saint Augustine Island.
Along with Lake Clark's volcanoes stand a frenzy of peaks called the Chigmit Mountains. John Kauffman once described the Chigmits "...as if colliding mountain waves had thrown up a sea of rock". In reality, the Chigmit Mountains were formed as a result of massive intrusions of granite coupled with the uplift of existing rock layers. The intruded rocks are moderately to highly deformed volcanic and sedimentary rocks. Today, we see a spectacular maze of jagged peaks and spires, and broad, U-shaped valleys carved out by glacial action.