Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
San Pedro River
by Mason Dominy
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
Links to information