Agathla's Needle (Agathla Peak) is a diatreme in the Navajo Volcanic Field erupted in the Oligocene or Miocene a little north of Kayenta, Arizona. Another eroded diatreme is the greenish hill at right. It is intruding into the Chinle Formation of Triassic age. Xenoliths carried in the diatremes of the Navajo volcanic field come from both the crust and mantle; these eruptions were thought to be short and violent. Several hundred meters of erosion has occurred since the eruption of these volcanics in the Four Corners area of the Colorado Plateau.