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Red Mountain

Wilfred Rockowitz
Physical Geology
Spring 2008    


Red Mountain Volcano In The San Francisco Volcano Field, Arizona.

History of San Francisco Volcano Field

     The San Francisco Volcano field is an area in northern Arizona, north of flagstaff, Arizona.  The field covers about 1,800 square miles of the southern boundary of the Colorado Plateau.

This field has about 600 volcanos, some are 6 million years old to less than 1,000 years old.

     Sunset crater is the youngest.  The highest peak in this field is Humphreys Peak and is Arizona’s highest peak which towers at 12,633.  Humphreys Peak is part of the San Francisco Peaks, an extinct stratovolcano complex.  However, we are going toexplore Red Mountain Volcano, and is one of the Volcano’s in the field.


Red Mountain

     Red Mountain is a cinder cone Volcano in the San Francisco Volcano field, about 25 miles northwest of Flagstaff, Arizona.  Red Mountain volcano is not your usual cinder cone, because it lacks the symmetry of most cinder cones.  Instead this volcano has a u-shape to it, and has a pretty cool Amphitheater that cuts into its cinder cone.  Also, it has these really neat erosional pillars called “hoodoos” that are all over the inside of the Amphitheater.  Red Mountain rises about 1,000 ft. above sea level, and is about 740,000 years old.  Red mountain is thought to be an extinct volcano.

Aerial view of Red Mountain cinder cone, Arizona

     Red Mountain, is one of hundreds of cinder cone volcanos in an area of 50 miles, and is an amazing place to visit with the inside exposed which is unusual.  It is not like most cinder cone volcanos in the San Francisco Volcanic Field.  Because erosion has not had enough time to expose their internal features.

      Right by Red Mountain is a large Forest Service sign along highway 180 invites motorist to stop and visit the cinder cone.  From the parking lot it is about a quarter mile off the highway.  From the parking lot it is just a 30-minute or so walk bring you to the entrance of the amphitheater carved right into the flank of Red Mountain.  The Back wall of the amphitheater is about an 800-foot cliff, which goes down slope to the left and right.  Standing inside of the amphitheater, you are surrounded by the towering cliffs of cinder, one would think that they were in the middle of the volcano, however the center of the eruption is over on the other side.


     The back wall of the amphitheater seen above is a feature that formed after the eruption and is still being enlarged by erosion today.

Cinder cones

     A cinder cone forms when the eruption happens on flat ground, deep in the earth, magma with gases (like a soda pop drink) rise throw a straight up and down pipe-shaped conduit like a fountain of gassy lava that can shoot up as high as an amazing 2,000 feet into the sky.

     As theses blobs of gassy molten rock fly through the sky, they cool fast enough to solidify before coming back down to earth.  A lot of gas stay in the fragments. These small fragments are called" cinders".  If the fragments are big, they are called volcanic bombs.  As the volcano continues to erupt these cinders, they pile up to form conical hills.


     Sometimes the sides of the growing hill become too steep causing the cinders to slide downwards. When the lava fountain ends, a balanced cone-shaped hill, indented by the cater, will be added to the landscape.  Inside the cone is a pile of loose cinders in layers that dip away from the vent of the volcano on all sides.

     In the last stages of the eruption, the magma loses most of its gas content.  Then when the gas is almost gone the fountain stop and a type of quite oozing runs into the cater or beneath the base of the cone as lava.  Here is a picture of the Red Mountain lava flow and it is a large field.  


Digital elevation model of the Red Mountain area, Arizona

My Visit to Red Mountain

When my wife and I visited Red mountain volcano I was in awe, and had never seen a Volcano up close.  Walking up to the volcano did not seem like much to me, however the closer we got to the volcano the picture stared to unfold.  I could not believe what I was seeing. The ground was full of black rocks of obsidian, clear quartz, pink quartz, and green olivine. The trail is about 1.5 miles a very easy hike despite the elevation change from (6,745 to 7,200 feet).  I remember walking along the path leading to the crater of the volcano, and all around was trees and bushes and suddenly everything changed.  My wife and I walked into this type of valley and the side started out gradually and kept getting taller the ground was solid rock.  I know now this was lava, hardly any trees the lava was rough very rough. You could cut yourself easily on the rough ground.  It seemed like I was walking into a very different world all at once.


The scenery was the most amazing thing I had ever seen in my life.  We had to climb the small set of steps that are shown in the picture (above) and the landscape changed even more.  The funny part is my wife and I had just left the Grand Canyon, and I thought Red Mountain was way better.  Then we got to the crater of Red mountain and now there was nothing around me but solid rock.   There was are these “hoodoos” all around me 10-20 feet tall all around me.


     I found it also wonderful how life could happen here trees and shrubs growing here as well.  It is not hard to spend hours inside Red Mountain walking around looking at all the formations.

Before I conclude please remember to go prepared, Arizona is not the place to go hiking without bringing plenty of water the climate is dry, and humidity is low.  It is easy to get dehydrated.  Bring some snacks as you will get hungry.  One more thing there is no cell phone service at, or inside of Red Mountain.