 The plateau developed through three volcanic cycles spanning two million years that included some of the world's largest known eruptions.Eruption of the > Huckleberry Ridge Tuff about 2 million years ago created the more than long Island Park Caldera.The second cycle concluded with the eruption of the Mesa Falls Tuff around 1.3 million years ago, forming the wide Henry's Fork Caldera at the western end of the first caldera.