Wednesday, July 06, 2011

To the Top of Arizona's Highest Peak - San Francisco Mountain

San Francisco Mountain is the highest point in Arizona, rising 12,633 feet into the sky. However, this strato-volcano has a collapsed top and if the former height of it were restored on the landscape today, the cone would top out at about 15,300 feet. This means that Arizona's San Francisco volcano might once have been the tallest mountain in the lower 48 states.

Back in the 1970's I started a tradition of hiking to the top of the San Francisco Peaks on my birthday. This past July 1 I did it again with my wife Helen.

The trail begins at an elevation of 9,200 feet and climbs through aspen and eventually the spruce-fir forest. The trail is quite shady on a summer morning but steadily climbs uphill.

Much of the geology is hidden beneath this veneer of vegetation but occasionally a block of andesite pokes through the green carpet and exposes vesicles, that formed when gas escaped as the lava hardened into rock.

We finally reached the saddle on the trial after only 2.5 hours. The elevation is about 11,900 feet. This is a view to the north and the summit area on Mt. Humphreys.

To the east is the Inner Basin of the Peaks and in the foreground you may notice a curved pile of talus rock. This is likely debris pushed into a ridge or moraine, when  Ice Age glaciers filled the Inner Basin and flowed to the east.

Does this bristlecone pine reveal the dominant wind direction. Agassiz Peak is seen in the distance, the second highest peak in the state.

We saw more flowers in the alpine zone than we did down below. Here small blue flowers frame the crest of this giant volcano.

Helen making her way up towards the summit. At this elevation, one must take a breath every few steps along the way.

There are numerous false summits on towards the top but here we can clearly see the crest.

This is the finally climb to the top! One last rubble strewn slope.

On top we found a small group of Boy Scouts from Gilbert enjoying the view.

For many years now, this stone wall has served as a wind protector. Surprisingly, there was no wind on top this day!

Helen taking a break on top of the mountain.

There is plenty of evidence of lightning strikes that have struck the top of the Peaks. Here is an example of a fulgarite where the rock was melted from the intense heat.

My official birthday shot for 2011.

Far off in the distance is the Grand Canyon and with my binoculars I saw Deva, Brahma and Zoroaster temples inside the canyon.

A view to the northwest and Kendrick Park (right) and Kendrick Peak (left).

This photo doesn't look like much but in the far distance (and perhaps too small in this photograph to appreciate) is a curious linear feature out on the grasslands. This is likely a fault and it is directed right towards the top of the San Francisco Peaks. I wondered, "Could this be a zone of weakness in the crust that these lava's took advantage of?"

Looking west to Kendrick Mountain (right), Sitgreaves Peak (center), and Bill Williams Mountain (left distance). These three lava dome volcano's were erupted along a fracture that is outlined by the position of the volcano's.

One last look from above the saddle before we headed down the slope.


  1. Great hike and Happy belated Birthday!

  2. Thanks Wayne for this guide ... our next trip to the top will be much more interesting (now we'll be looking for fulgarite).

    You certainly chose the perfect day to hike up there (besides being your birthday).

  3. Forgot your birthday but my thoughts are with you and what a great way to celebrate! Thanks for sharing these exciting photos.


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