Inner Crater of the San Francisco Peaks

The inner crater of the San Francisco Peaks formed sometime before the emplacement of Sugarloaf dome about 82,000 years ago (Pleistocene). The crater is the result of flank collapse and debris avalanche which transported the rock material several miles east. According to Dr. Richard Holm, Professor Emeritus | Northern Arizona University, the debris avalanche deposit is located beneath a broad meadow just west of Sunset Crater.