Part D

Geology of the San Francisco Mountain Area

Quaternary volcanic rocks are important components to many terranes around the world, and are displayed on many different geologic maps. This is certainly the case in Arizona, where several areas of the state witnessed volcanic eruptions during the Quaternary. The Flagstaff area is home to the San Francisco volcanic field (SFVF), with over 600 individual volcanic vents and many outstanding examples of different volcano types. To learn more about the main feature in the SFVF, let's look at the geology of the San Francisco Mountain area by reviewing the Geologic Map of San Francisco Mountain, Elden Mountain, and the Dry Lake Hills, Coconino County, Arizona. San Francisco Mountain is the main landform on the map and is crowned by several peaks, including Doyle, Fremont, Agassiz, Humphreys (the highest point in Arizona), Aubineau, and Reese.

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Geologic Map of San Francisco Mountain, Elden Mountain, and the Dry Lake Hills

 

Answer Quiz Me! questions D30 through D48 using the Geologic Map of San Francisco Mountain, Elden Mountain, and the Dry Lake Hills (see the PDF link below). The questions refer to the geologic map, Description of Map Units, Correlation of Map Units, and cross section. If necessary, refer to your rock identification charts (Igneous HERE / Metamorphic HERE / Sedimentary HERE) and the Volcano Review Table (see PDF HERE).

  

Fern Mountain & Hart Prairie

Fern Mountain and Hart Prairie are located near the west edge of the map near 35° 20'N, 111° 44' W.

Quiz Me! / D30

 

Quiz Me! / D31

 

Quiz Me! / D32

 

 

Elden Mountain

Elden Mountain is located in the southeast part of the map at 35° 15' N, 111° 36' 30" W

Quiz Me! / D33

 

Quiz Me! / D34

 

Quiz Me! / D35

 

Quiz Me! / D36 

 

 

Sugarloaf Mountain

Sugarloaf Mountain is located in the northeast part of the map at the northeast end of the Interior Valley near 35° 22'N, 111° 37' W. 

Quiz Me! / D37

 

Quiz Me! / D38

 

Quiz Me! / D39

 

Quiz Me! / D40

 

 

San Francisco Mountain

San Francisco Mountain is the main topographic feature on the map and is crowned by several peaks, including Doyle, Fremont, Agassiz, Humphreys, Aubineau, and Reese. Humphreys Peak, the highest point in Arizona, is located near the center of the map around 35° 21'N, 111° 41' W.

Quiz Me! / D41

 

Quiz Me! / D42

 

Quiz Me! / D43

 

Quiz Me! / D44

 

Quiz Me! / D45

 

Quiz Me! / D46

  

Quiz Me! / D47

 

 

 

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Geology of San Francisco Mountain

Let's look more closely at a geologic cross section of the San Francisco Mountain area, located in the heart of the San Francisco volcanic field of northern Arizona.

 

Answer Quiz Me! questions D49 and D50 using the San Francisco Mountain sequence diagram (Figure 15-11). Print a hard-copy of the diagram if necessary (see the link below for a printable PDF version). Also refer to the Key to Map Fill Patterns (see PDF HERE) and your rock identification charts. 

Quiz Me! / D49