Arizona Road Trip Jan-Feb 2016 Part 9
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Arizona Road Trip Jan-Feb 2016 Part 9
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Miscellaneous (2)

Lichens in the Superstitions & Lower Salt River

Assortment of crustose lichens along trail into Superstitions.

Verrucariaceae: Dermatocarpon americanum (Stippleback Lichen)

Note: This leathery, foliose lichen is attached to the substrate by an umbilicus like rock tripes of the genus Umbilicaria. Unlike Umbilicaria, it belongs to an entirely different family that is characterized by perithecia rather than apothecia. In fact, the numerous sunken perithecia appear like tiny black dots on the upper surface of the thallus. This species is listed as D. miniatum in some references.

Numerous sunken perithecia appear like tiny black dots on the thallus.

  Dermatocarpon in San Felipe Valley, San Diego County   

Rock Types In The Complex Superstitions

The Superstitions have a complex geologic history dating back more than 25 million years. They are composed of a variety of extrusive volcanic rocks including basalt, dacite, andesite, rhyolite and welded tuff. The above sample contains some of the common rocks in the alluvial areas on western side of the Superstitions.

Porphyritic andesite with crystals of plagioclase feldspar. This igneous rock was extruded from ancient volcanoes that formed the Superstition Mountains. It is common in the alluvial areas on the west side of the Superstitions. Some references refer to the alluvial rocks as mostly welded tuff, dacite and decomposed granite.