On the west side is the San Luis Valley, a portion of the Rio Grande Rift. On the southeast side is the Raton Basin, a quiet but still active volcanic field. On the northeast side are the Wet Mountains and the Front Range, areas of Precambrian igneous and metamorphic rocks formed during the Colorado orogeny some 1.7 billion years ago and then uplifted more recently during the Laramide orogeny.