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San Francisco Peaks Alpine Information: San Francisco Peaks Groundsel Vs. Alpine Avens
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San Francisco Peaks Alpine Information: San Francisco Peaks Groundsel Vs. Alpine Avens

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San Francisco Peaks Alpine Information: San Francisco Peaks Groundsel Vs. Alpine Avens

Page Type: Article

Object Title: San Francisco Peaks Alpine Information: San Francisco Peaks Groundsel Vs. Alpine Avens

Activities: Hiking, Mountaineering

 

Page By: Humphrey

Created/Edited: Dec 6, 2010 / Dec 6, 2010

Object ID: 683242

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Page Score: 84.82%  - 19 Votes 

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Arizona's Only True Alpine Area

The San Francisco Peaks are an extinct strato volcano in northern Arizona. The two highest points in the state are located on the mountain; Humphrey's Peak (12,633') and Agassiz Peak (12,356'). Within the state of Arizona, no other alpine areas exist. The closest one will get is the White Mountains of eastern Arizona and Mount Baldy. However, Mount Baldy has a much lower summit (11,420'). That is less than the San Francisco Peaks lowest summit, Doyle Peak (11,460'). Baldy is much more gentle in appearance than the relatively steeply sided San Francisco Peaks, and it lacks any true alpine environment as no part of the mountain is really above treeline. 
Agassiz Peak in Green
Agassiz Peak from the Humphrey Summit Trail


Only the western and highest part of the San Francisco Peaks is Alpine. Fremont Peak (11,969') barely breaks it, but has small seedlings growing at it's summit and the remaining peaks all have trees on them. The treeless area does extents to lower altitude than some of the other peaks, and in these places alpine plants are found. However, large, small, and wind blown trees are found growing in protected places above some of these lower alpine or treeless areas. It is in the alpine areas of the San Francisco Peaks that some of Arizona's rarest plants grow, and one of these plants is found nowhere else in the world.

The Peaks Alpine Environment

When a person visits the San Francisco Peaks at a time the mountain does not have snow on it, the first thing they will probably notice is the near absence of vegetation. The Peaks are a dry and windy place. Probably the only time of the year the wind isn't fierce is during the summer monsoon season. Calm periods can exist at any time of year, but wind seems to be more common. Spring is the worst time of year for wind, and March to June is the worst time of year to be on the Peaks. 
Slope populated mostly with Alpine Avens
Limited vegetation on rocky slopes


Because of all the wind, the Peaks dry out quickly. In winter, snow gets blown of the mountain very quickly. Dry, powdery snows don't last more than a day or two. What doesn't blow away melts rapidly under our warm sunny days. Above treeline, this dry environment combines with unweathered and rocky conditions to make an environment that doesn't support much plant life. Indeed, some slopes seem to have no vegetation on them at all.

Protection

As a result of the rare qualities of the mountain, it is afforded some protection. This might seem odd given the appearance of it and the feeling that there is nothing there worth protecting. However, alpine plants do exist on the Peaks. Some are common and some appear common but are endemic to the mountain and considered rare. Human trampling of the vegetation adjacent to the trail is a problem in some places and it is best to avoid stepping on any of the alpine plants.

San Francisco Peaks Groundsel

San Francisco Peaks Groundsel (Senecio franciscanus) is considered endemic to the mountain and is listed a "threatened" species. The threat seems to be mostly from it being rare and the potential for hikers to destroy it. There is actually a lot of it on the mountain and it does quite well up there, often growing right by trails. As long as people don't step on it, it survives well.  
San Francisco Peaks Groundsel
San Francisco Peaks Groundsel


While climbing Grand Teton in August of 2010, I came across a very similar looking plant. It turns out that there are many species of Senecio, and the one I spotted in the Tetons is similar in appearance, but not the same species as is found on the San Francisco Peaks. Still, telling the difference is hard. In the two pictures, one is from Arizona and one from Wyoming. The Wyoming plant grows near a granite rock. We have no granite on the San Francisco Peaks. 
Wyoming Teton Range Senecio
Wyoming Senecio from the Teton Range
 
Senecio franciscanus
On Fremont Peak


Officially, protecting the alpine area and the San Francisco Peaks Groundsel is the reason Agassiz Peak hiking and any off trail hiking is prohibited on the San Francisco Peaks. Because of this, it is a good idea to recognize the plant and make efforts not to trample it. If you stick to the trails, you won't have any trouble avoiding it.

Alpine Avens

Alpine Avens (Geum rossii) is the other common yellow flowering plant of the San Francisco Peaks. This is a very common alpine plant in the west. I have heard people comment that this is the rare protected plant of the mountain, and these have been Flagstaff dwellers, but it is not. The plant is valuable on the mountain, and in recent years I have noticed hikers trampling the patches of Avens that grow along the trail. Some of these have been killed and this is causing erosion around the trail. It is best to stay on trail and to step on large rocks if letting someone pass. The more you step on the plants the harder it is for them to survive.  
Alpine Avens
Alpine Avens
 
Alpine Avens
More Avens

Images

Alpine and Humphrey\'s PeakAgassiz and the upper CirqueSan Francisco Peaks GroundselAgassiz Peak in GreenWyoming Teton Range SenecioAlpine AvensAlpine Avens
In the saddleSlope populated mostly with Alpine Avens

Comments


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lcarreauHello Mr. Leghorn..

lcarreau

Voted 10/10

This report on the SFP Groundsel is long overdue.

Every so often, somebody writes in the forum:
"WHY can't I climb Agassiz when there's no snow on it ???"

I hope this report will answer their question.
Happy Holidays, man..
Posted Dec 12, 2010 11:00 am

Alex WoodNice

Alex Wood

Voted 10/10

I like the article and it is definitely needed. A few scientific inputs though..... A big reason the climate is so dry on the peaks is the fact that they are made out of basalt, which has little to no moisture retention. Basalt sucks up any moisture leaving no groundwater, which is partly due to its unweathered nature (the peaks are young geologically), but mostly due to the fact that that is just the nature of basalt.

For flora diversity- The big thing to take away here is that the alpine tundra is essentially an island. If change occurs, there is really no possible way for these plants to adjust to a different location due to the fact that the nearest alpine tundra aside from the peaks is well over 200 miles away. So because of this, the alpine flora is refined over and over again resulting in a unique varieties of species (evolution). Groundsel and bristlecone pines located on the peaks can be found elsewhere and are diverse, however changes that occurred as a result of isolation , especially above treeline, result in highly diversified flora species and in the case of the grounsel, the only know species. I know you brought up the fact that its the only place in AZ like it and how the environment effects these flora rarities, but isolation is the key reason the San Francisco Peaks have such rare alpine flora. The flora are on the edge of an environment and cannot go up or down because of this isolation from other like environments. This makes the alpine tundra extremely diversified.
Posted Dec 13, 2010 8:12 pm

Clark_GriswoldRe: Nice

Clark_Griswold

Voted 10/10

Thanks, but I have heard the Peaks are mostly Andecite, which is a rock similar to basalt but with a slightly different mineral composition. On the silica scale, it's about half way between Dacite, which forms Elden and some of the lower faces of the Peaks, and Basalt. True basalt just won't rise up like the Peaks, but can look like the Heart Prairie Shield volcano. And yes, the isolated nature of the peaks is responsible for the speciation of the sennecio from other related species, much like Kaibab and Abert's Squirrels.
Posted Dec 13, 2010 11:58 pm

Alex WoodRe: Nice

Alex Wood

Voted 10/10

Most of it is basalt, with parts (like you said at the base) being dacite and then some of the more sheer outcrops are andesite. Basalt can definitely be found in most of the upper portions of the peaks. Either way, any of those rocks have super low moisture retention.
Posted Dec 14, 2010 1:56 am

Clark_GriswoldRe: Nice

Clark_Griswold

Voted 10/10

No, it is not mostly basalt. Basalt can not support the steeply sided formations you see on a stratovolcano like the Peaks. Basalt forms shield volcanoes and the large flows we have around town in our volcanic field. Read the parts on stratovolcanoes and San Francisco Mountain. The dominant rock is Andecite, according to every other source I have read or heard from, including senior NAU geology majors.

http://geopubs.wr.usgs.gov/fact-sheet/fs017-01/

http://vulcan.wr.usgs.gov/Volcanoes/Arizona/description_arizona_volcanoes.html

Or, this direct quote:
"San Francisco Mountain is a stratovolcano composed of andesite, dacite, rhyodacite, and rhyolite flows and pyroclastic deposits. It is surrounded by approximately four hundred basaltic cinder cones and associated flows, and by scattered silicic domes and dome complexes."
the above was found on pg 105 of:
Karen J. Wenrich-Verbeek, The petrogenesis and trace-element geochemistry of intermediate lavas from humphreys peak, san francisco volcanic field, arizona, Tectonophysics, Volume 61, Issues 1-3, 30 December 1979, Pages 103-129.

I found that article through NAU's library and Science Direct. As a fellow student, you should be able to view the material. The article mentions basalt in the surrounding volcanic field, but it is not a feature on the mountain.


While much of the water that falls on the mountain percolates down into local aquifers, like the one the city has wells into in the Inner Basin, the difference between volcano vs other rock types is slight in regard to water retention when you consider the relative lack of precipitation, the steep slopes, the high winds, and the low weathering above treeline. In monsoon season, we don't have the winds we do at other times of year and the rain is sufficient to keep the soil moist. For much of the rest of the year wind scours off the snow, and removes what moisture does make it into the soil. That isn't just a problem on volcanic mountains.
Posted Dec 14, 2010 12:00 pm

lcarreauRe: Nice

lcarreau

Voted 10/10

Sorry to interject, but that's an excellent point you made regarding the high winds.

Gotta agree that the "availability of water" remains a sensitive
issue. Just curious, but have you ever visited the "lava tube caves" to the SW of the Peaks. That explains how much of the
water actually finds its way into the ground.

P.S. - Personally, I have gained a much GREATER respect for the
"San Francisco Peaks volcano" after reading your article.

Outstanding job, Mister Leghorn! !
Posted Dec 15, 2010 2:56 pm

Alex WoodRe: Nice

Alex Wood

Voted 10/10

Theoretically, the reason why stratovolcanos have andesite and rhyolite is because silica content in the magma changes as the volcano matures. I have always been told too that its andesite up there too. I was talking to one of my volcanologist professors at NAU and she was saying how she thinks there is a possibility of the majority of the rock type on the peaks to be a mix of basalt and andesite, which I think is true after cracking opening a dozen rocks along the rim, the crystal size and composition is similar to that of the same deposits on other nearby peaks. I have definitely seen all andesite intrusions high up on the peaks, but most of the rock along the rim is very black in color, which is more like basalt. There is still lots of discrepancy about the Peaks geologically speaking. Still think you have a good page!
Posted Dec 22, 2010 2:22 am

glidermanRe: Nice

gliderman

Hasn't voted

A couple of side notes to all this.... If you get to the very top of Humphrey Peak, look carefully at the surface of the rocks. The southeast quadrant within about 30 feet of the tip top looks like it has prune juice spattered on it. These areas are actually geologic oddities called "fulgerites" which are created by the instant heat of lightning strikes that melt small portions of the rock. A friend an I mapped them for the Museum of Northern Arizona geology department back in the 60's. I'm not sure what meteorologic or geologic reasoning was behind 90% of the strikes to be in that particular area (90 degrees to 180 degrees on the compass), but for sure, it is NOT the place to hunker down if you happened to be there as a storm came along!

Another oddity of the Peaks... if you look at them from the south, such as from Flagstaff, there is an area that loses its snow cover first, appearing as sort of a bald spot in the snow. It is about 1/5 of the way down from the top and to the left of center when looking north. We always referred to it as the "hot spot", anthough that is just a relative term. A study of the area determined it was connected to deep fractures which allowed air from much lower down to be sucked up during atmospheric pressure changes. With a dry adiabatic rate of about 3 1/2 degrees / 1000 feet, this air coming up through the fractures was much warmer / far less cold than the ambient temperature at the surface of the mountain at that point, resulting in the snow cover melting / evaporating / subliming faster there than on much of the rest of the area above treeline that faces south. The area also gets some downforce winds (rotors) during some wind events, compounding the snow loss.
Posted Dec 21, 2010 4:29 pm

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