The San Francisco Peaks are a volcanic mountain range located in north central Arizona. In 1629, one hundred and forty seven years before San Francisco, California received its name, Spanish Friars founded a mission at a Hopi Indian village in honor of St. Francis. 17th century Franciscans gave the name San Francisco to the peaks to honor St. Francis of Assisi, the founder of their order.
Three of the summits ring this dormant volcano's now quiet inner caldera. The highest summit in the range, Humphreys Peak (12,633 feet /3,851 meters), is the highest point in the state of Arizona. The San Francisco Volcanic Field, which covers about 1,800 square miles, is part of northern Arizona’s spectacular landscape. San Francisco Peaks is the only stratovolcano in the volcanic field and was built by eruptions between about 1 and 0.4 million years ago. Stratovolcanoes have moderately steep slopes and normally rise to a central peak and are built up by countless eruptions over hundreds of thousands of years. Since the eruption, much of the San Francisco Peaks has been removed to create the "Inner Basin" (another popular hiking trail runs here). There are two competing theories about the process: the missing material may have been removed quickly and explosively by an eruption, or it may have been removed slowly by a combination of large landslides, water erosion, and glacial scouring.
After visiting the Snowbowl resort area we came down to US 180 (the highway which leads to the Grand Canyon). From here we took a loop around the peaks. This drive took us all the way around Arizona's highest mountain, winding through a land of pine forests and aspen groves, open prairies and rustic homesteads. We enjoyed this trip in September but anytime is a good time to enjoy this drive, although a ranger said the roads are closed through much of the winter. Autumn started to turn the mountain to gold, filling forest roads and trails with visitors come to enjoy the colorful display.
From US 180 we turned right to forest road FR 418. Many parts of the road covered with gravel; drive slowly. We met several groups of visitors traveling on safari jeeps (dust in the air for miles). There are a number of places along this route where you can stop to take a hike, or enjoy a picnic lunch. In two places we saw vacationers set up a primitive camp (Potato Tank and Reese Tank homesteads area). Shortly after Reese Tank a scenic overview offers scenic view of the Sunset Crater volcanic area. The winding rocky road brings you down to US 89 (12 miles to Flagstaff). Allow 2 -3 hours to enjoy the trip.
It is possible to drive around the peaks counter clockwise (e.g. from US89 to US 180). In this case you can add to the itinerary a visit to the Lava River Cave. This mile-long lava tube cave was formed roughly 700,000 years ago by molten rock that erupted from a volcanic vent in nearby Hart Prairie. From US 180 turn left (west) on FR 245 (at milepost 230). Continue 3 miles to FR171 and turn south 1 mile to where FR 171B turns left a short distance to Lava River Cave. The cave entrance is 300 yards east of the end of the road. Look for a large circle of rocks that mark the cave entrance; study the cave map before entering. The entrance is actually a hole in the ground and the floor just inside is covered with large, slippery boulders. This cave has a year round temperature of 34 degrees. You will need to dress warmly, wear sturdy shoes and bring adequate lighting in order to make the most of your visit (conditions throughout the cave are cold and dark). A Coleman lantern is a good idea. Approx 0.5 miles in there is a fork. Take the left fork -- the ceiling of the right fork drops down to about a yard off the floor. Towards the end of the tunnel, there are several areas where the ceiling gets kind of low -- just keep going. Check with Flagstaff Tourist Information Office if the road FR171 is open (may be closed due to rains).