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Roger Weller, geology instructor

San Pedro River
by Mason Dominy
Physical Geology
Spring 2010
                                                   The San Pedro River


            The San Pedro River flows from Sonora, Mexico, all the way to the Gila River in between Tucson and Phoenix, Arizona. It is one of the last rivers in Arizona that naturally flow all year long. The river was created millions of years ago when the surrounding area was full of lakes during the ice ages. The water brought gravel down and carved out what is now the river.The San Pedro Riparian area is in Cochise County, and covers almost 57,000 acres.

 Photo credited to Roger Weller

            There is a lot of vegetation along the San Pedro, which is very rare for the desert. There are cottonwood trees, willows, mesquite trees, and the endangered Huachuca water umbel.


Photo by Harold E. Malde


This area is home to many different animals. The northern flowing river is home to over 80 species of mammals, 14 species of fish, 65 species of reptiles and amphibians. It is also home to over 100 species of breeding birds, and over 250 migratory birds, making one of the best places in the world for bird watching.

Photo by Friends of the San Pedro River



Many fossils have also been discovered around the San Pedro Valley area, the most famous being the Lehner Mammoth Site. Evidence has been found showing that prehistoric hunters killed and cooked mammoths.

Photos by virtual tourist

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