Amboy Crater is a 250-foot-high ash-and-cinder crater 1,500 feet in diameter in one of the youngest volcanic fields in the United States. Six distinct periods of eruptions created a nested group of volcanic cinder cones encompassing 24 square miles. Volcanic activity began an estimated 6,000 years ago, and the last period of eruptions occurred as recently as 500 years ago. Its recent origin and near-perfect shape led to its designation as a National Natural Landmark in 1975, and from the rim there is an outstanding view of the associated lava field and surrounding desert area.