HERPETOLOGY OF ZUNI MOUNTAINS — GEHLBACH 245 



I am very grateful to each of the above persons and institutions. 

 I am equally indebted to the Prairie Trekers, whose efforts in my 

 behalf produced many specimens and much inspiration; I dedicate 

 this paper to them. 



Physical and Climatic Environments 



The study area, referred to as the Zuni region or Zunis, includes 

 most of McKinley and Valencia Counties, New Mexico (fig. 1). It 

 is situated in portions of both Datil and Navajo Sections of the 

 Colorado Plateau at the southeastern extremity of this physiographic 

 province (Hunt, 1956, fig. 1). Elevations range from 5794 to 11,389 

 feet. The diverse topography and semiarid climate, with their 

 attendant effects on vegetation, greatly influence herpetofaunal 

 distribution. 



Topography 



Most spacious of the various topographical features are the Zuni 

 Mountains, a domal uplift approximately 25 miles wide and 70 miles 

 long, lying northwest by southeast near the southeastern edge of 

 the Colorado Plateau. Strata surrounding the dome are gently 

 sloping Pennsylvanian through Cretaceous formations, mostly sand- 

 stones (Fenneman, 1931, pp. 217-319). Rock outcrops are exposed 

 in canyons, mesas, and the great retreating cliffs characteristic of 

 Colorado Plateau topography. These major erosional features 

 probably were formed no earlier than the Miocene and, along with 

 the entire Plateau, have been uplifted in Pliocene and Pleistocene 

 times (Hunt, 1956). The summit of Mount Sedgwick at 9156 feet 

 is the highest point above the basal plain, which averages 7000 feet. 



Running along Oso Ridge, the Continental Divide separates the 

 Zuni Mountains almost equally into eastern and western watersheds. 

 The former is partly drained by Azul and Bluewater Creeks, which 

 flow into the Rio San Jose and ultimately into the Rio Grande. The 

 latter is drained by the Rio Puerco (this name is also given to a stream 

 of the Rio Grande basin), Rio Nutria, and Zuni River, which empty 

 into the Little Colorado River. All streams, except the headwaters 

 of the Zuni, are intermittent, and steady flow occm"s only during the 

 summer period of heaviest precipitation. Bluewater Lake and 

 Ramah Reservoir are relatively permanent man-made features. 



Between the Zuni Mountains and other structural upwarps are 

 broad, open valleys such as the Gallup-Zuni Basin. The strata of 

 this basin slope gently westward from the Zuni Mountains, decreasing 

 from 8000 feet to 6500 feet toward the mouth of the Zuni River. 

 Such features give the region its continuous yet vertically diverse 

 aspect. To the north, gently undulating topography of the Navajo 



