Important mountains

So why do I call them important mountains? What distinguishes these big heaps of rocks from others in our vicinity? For starters, today's pictures are of important mountains to the north of town; I captured the images on Sunday as we headed to (and from) Chino Valley, which is reasonably flat and serves to highlight, for example, Bill Williams which is due north of SR 89 for much of its length. As you can see, this particular volcanic peak stands by itself. In fact, all my important mountains are notable for standing quite apart from their surround.

As do the Sullivan Buttes, to the NW of Chino Valley. As I recall my geologic map of the area, the buttes are neither granitic nor volcanic, but instead limestone. There's some fascinating real estate up in the middle of this formation, BTW.

Although Granite Mountain is not really free-standing, it is nonetheless outstanding because it is a couple of thousand feet higher than the nearest peak to the left, Little Granite. The view from SR89 is revealing as it shows the long tail of Granite that extends far to the north.

The glorious sight to the north, however, in all seasons is San Francisco Mountain -- known locally as The Peaks. By last Sunday, enough snow had fallen in the high country to outline the top. As an exercise, let your eyes follow the lines on the extreme east and west upward to sketch in what once was a much taller mountain, similar to Fuji. According to the US Geological Service, San Francisco Mountain is the only stratovolcano in the San Francisco volcanic field and was built by eruptions between about 1 and 0.4 million years ago. Since then, much of the mountain has been removed to create the “Inner Basin.” The missing material may have been removed quickly and explosively by an eruption similar to the 1980 eruption of Mount St. Helens, Washington, or it may have been removed slowly and incrementally by a combination of large landslides, water erosion, and glacial scouring. If you want to track the weather at The Peaks, here's a webcam.

My favorite view of The Peaks is at the top of Willow Creek Road heading north; as you round a bend, suddenly the huge mountain looms. Zap. In your face. An exhilarating moment! And, yes, I'll get around to identifying the important mountains to the south one of these days. Real Soon Now.

Linkage: Choice links to flowers and green, growing plants are featured at this month's Berry-Go-Round, a botanical blog carnival. And just to show that there's a blog for about any subject you might imagine, you should go visit Cake Wrecks. That's right, a place to memorialize baking disasters.

Arizona Hot Spot

When your daughter and family move to a house situated smack dab on the Pacific Rim of Fire, you can bet you're going to be interested in volcanoes. Of course, I've been intrigued by volcanoes for many years; in fact, I put the Kamchatka Peninsula on my list of remarkable places in the world I'd like to visit but never will.

And so it was that I joined the crowd at the Sharlot Hall Museum this afternoon to hear Wendell Duffield's quite informative lecture on Northern Arizona volcanoes. More specifically, the San Francisco volcanic field surrounding Flagstaff. Full house -- people in Prescott are interested in the subject. After all, we have a couple of tired old relics in the area and lava flows here and there, even in town.

Admittedly, Yavapai County, with its odds and ends of vulcanism, isn't going to interest geologists when next door there's an incredible field of mountains and cones. Every one of those dots on the map above is a volcanic eruption of some sort; the current count is over 600, dating from 6 million years ago up to 1250 AD. And, no, the field is not dead; it is moving to the northeast at the rate of about 2 inches per year and could spring into action one of these days. It is sufficiently un-dormant that Duffield was part of a US Geological Service team who recommended it as a potential source for geothermal energy.

Flagstaff is located at the foot of San Francisco Mountain, at roughly 12,600 ft. tall the high spot in Arizona. Presumably it was a stratovolcano that blew out its side about one million years ago, a la Mt. St. Helens. Probably a good 16,000 ft. in elevation before the big event. Incidentally, Duffield pointed out that the mound in the lower right dates from only about 400,000 years ago.

Here's another feature of the field, in a Landsat image. The black cone is SP crater, with a major lava flow to the north. Don't miss all the volcanic cones at the bottom of the image.

Two types of mountain projected at the lecture. The illustrations are from a book written by the speaker.

Here is evidence to remind us of the recency of vulcanism in Arizona -- Indian corn left an imprint in a piece of lava found near Sunset Crater, our latest volcano. But even more intriguing is the pottery shard embedded in lava (below) from the most recent flow from a cone at the foot of remote Mt. Trumbull, which is located at the west end of Grand Canyon Natl. Park on the north rim. Both these relics are believed to be in the same age range, said Duffield.

Judging from the questions the audience threw at the speaker, there's really a lot of interest in local vulcanism, which doesn't make it into most discussions, such as these from the US Geological Service (here and here.) Of course I bought a copy of Duffield's book, Volcanoes in Northern Arizona. And one of these days I might pull together a post about a few of the volcanic features of our local area.