How would you like to visit a volcano in Arizona? Do we have dormant volcanoes in Arizona? The whole Tucson area is scattered with former volcanoes, big and small. All children learn best by hands on learning, or get enthused to read more facts after they experience it.
Necks – solid formations formed as magma rises and cools inside a cone, That later is left behind after the soft deposits erode – can be found in many places if you know how to look for them. Picacho Peak, because of its sharp, peaked shape, was thought to be a volcanic neck. It is not, but a hike there could illustrate what a neck might look like.
The Catalina Mountains, to the north, are the result of volcanic action and a volcano, 70 million years ago. Later geologic action caused the top of that volcano to break loose and slide 20 miles west, forming the Tucson Mountains. One large hill, Snyder Hill, covered with sea animal fossils, is believed to have slid west across the Tucson basin as the Rincon Mountains rose in a batholith. Find more details, and an interactive illustration.
Sentinel Peak ,or “A” Mountain, shows different layers of volcanic ash and lava. However, it is the remains of a side slope left after the volcano was eroded away by the river.
The volcano map does not show any signs of probable renewed activity close to Tucson. However, south-east of Tucson, the San Bernardino volcanic field still has hot springs, testifying to lingering heat in the subsurface. 130 vents form the San Bernardino field, mostly cinder cones. The most prominent vent is Paramore Crater, nearly one-mile in diameter and 200 feet deep. The hot springs remain even though the field was active between 1 million and 27,000 years ago.
The most famous and most recently active volcano in Arizona is Sunset Crater near Flagstaff, which erupted less than 1,000 years ago and has been a National Monument since 1930.
In their fact sheet, Priest, Duffield, Malis-Clark, Hendley II, and Stauffer explain that “all hills and mountains between Flagstaff and the Grand Canyon are geologically young but extinct volcanoes of the San Francisco Volcanic Field.” U.S. Geological Survey (USGS) scientists believe it is likely that eruptions will occur again in the San Francisco Volcanic Field. The average interval between periods of volcanic activity is several thousand years. However, it is impossible to forecast when the next eruption will occur.
The USGS provides more information on volcanoes, and easy to read classifications of magma, including ash, “bombs“, and lava. For instance, avalanches and mudflows cause more damage than the volcano.
For fun answers and information to the question: If volcanoes cause diamonds, how come Arizona has no diamonds? Check Clay Thompson’s blog. The simple answer, volcanoes need carbon to form diamonds. Not all volcanoes have carbon.
So, interest your child in news of volcanoes. Take a field trip up “A” mountain to observe the different layers of ash, seen in the road cuts. Near the big “A” and on top, places can be found of hard, flattish, black rock, where lava flowed. The white rock is not magma, but caliche – a calcium deposit.
Take a trip to Sunset Crater National Park to see our most recent volcano. The trails there are wheelchair accessible. Make learning live. Make it outdoors. Make it fun.