Geology of the Chiricahua Mountains

Cochise College    
Bisbee and Cochise County                                         

Geology of Southeastern Arizona
Arizona Geology
Geology Home Page

Roger Weller, geology instructor     3/26/18

Chiricahua Mountains

general geology

The Chiricahua Mountains are geologically similar to neighboring ranges to the
east in New Mexico. These ranges are largely made up of Tertiary volcanics, including
rhyolitic ash-flow deposits, rhyolitic to basaltic flows, and associated breccias. The
volcanic deposits are part of a large volcanic field, which includes the Chiricahua
Mountains, the central and southern Peloncillo Mountains, and the Animas Mountains.


Six major ash flows and a capping rhyolitic volcanic flow make up the Rhyolite
 Canyon Formation in the Chiricahua Monument region. The ash flows are distinguished
from each other by their color, jointing, texture, phenocrysts, composition, and weathering
characteristics.  A light brownish gray welded rhyolitic tuff and a brittle, pinkish-gray
welded rhyolite tuff are the only rocks forming prominent columns in the Monument. 
The light brownish gray, column-forming, welded rhyolite tuff has been radiometrically
age dated at about 25 million years old.



Maps of the Chiricahua Mountains 

Views of the Chiricahua Mountains
list of references
Published references related to the Chiricahua Mountains
articles (online)
1. Guide to the Volcanic Geology of the Chiricahua National
 Monument and Vicinity, Cochise County

 by John S. Pallister, Edward A. du Bray, and
 Douglas B. Hall, 1997
 pamphlet to accompany
 U.S.G.S. Miscellaneous Investigations Series Map I-2541, 11p.

2. Chiricahua National Monument, by JoAnn Deakin. 2009

  Volcanic Geology of the Northern Chiricahua Mountains by Evans B. Mayo, 1959,     
  Guidebook II, L.A. Heindl, ed., Arizona Geological Society
  p. 134-138                                                                                


student presentations on the Chiricahua Mountains
1. Hiking in the Chiricahua National Monument, Arizona-Vivian Lewis  (Fall 2005)

2. The Chiricahua National Park, Arizona-Kim McGee  (Fall 2005)