Jemez Caldera

Like almost any geological feature in New Mexico, the Jemez Mountains have a remarkable story to tell. We begin roughly ten million years ago. Basaltic and rhyolite Magma is pushing up from the earth’s mantle and the Jemez volcano is growing larger and larger. By about 2 million years ago, a snow-covered peak rises almost 40,000 feet into the sky and is perhaps the world’s largest volcano for that time. We are now at 1.4 millions years ago and you are about to witness one of natures most powerful and destructive displays. The tremendous pressure built up from the past 10 millions years is let loose by a series of fantastic volcanic eruptions. Over 100 cubic miles of ash, pumice and broken rock was spewed out across the countryside, covering more than 1500 square miles that was in some areas up to 1,000 feet deep in ash. These eruptions were about 600 times more powerful than the 1980 eruption of Mount St. Helens. In fact, this volcano ejected so much material that the interior was left hollow and the mountain collapsed into itself forming what is now the Valle Grande, a cliff-ringed crater more than 14 miles across.