14 BUREAU OF AMEEICAN ETHNOLOGY [bull. 54 



of information above mentioned. Local archives will yet yield 

 much of value, as will also, in much larger degree, those of Mexico, 

 but doubtless the chief source to which we must go is the Archivo 

 General de las Indias in Spain. 



Accordingly a series of papers will be presented dealing not only 

 with the ancient monuments and excavations but also with the 

 ethnology, documentaiy history, and ])hysical geography of the 

 region. 



As yet the geographers and geologists have furnished no thorough 

 studies of the Rio Grande valley. There are available the maps of 

 the Wheeler Survey, which are substantially correct for leading topo- 

 graphic outlines, and early sheets of the United States Geological 

 Surve}^, which are useful, though inferior to those of later issue 

 covering other sections. The reconnoissance reports of the Macomb, 

 Wheeler, and Hayden expeditions refer to the broader Imes of geologic 

 topography. In recent years the University of New Mexico has 

 made important studies on the geologic history of the vicinity of 

 Albuquerque. 



The Rio Grande valley embraces the Pueblo region that belongs 

 to the Atlantic side of the continental divide. The section here 

 considered lies between 36° 30' and 35° 15' north latitude and be- 

 tween 105° 30' and 106° 50' west longitude; roughly, it is that 

 portion of the Rio Grande valley which lies between Taos and Berna- 

 lillo, New Mexico, a distance, north and south, of 75 miles. This 

 drainage area is approximately 75 miles wide. We are discussing 

 then a section of country about 75 miles square, an area of about 

 3,600,000 acres. Physiographically it affords a satisfactory type- 

 section of the Rio Giande basin. It embraces the principal foci 

 of ancient population of the valley, and within its boundaries are 

 villages representing all the surviving ethnic groups of the eastern 

 Pueblos. 



The Rio Grande enters this quadrangle in longitude 105° 45' and 

 leaves it at a point 50' meridionally (approximately 50 miles) to the 

 west. The general trend of the valley is thus from northeast to 

 southwest. The fall during this course is from an altitude of 7,000 

 to one of 5,000 feet above sea level, this being accomplished by a 

 gradual descent, no falls and no considerable rapids occurring at any 

 place. At its point of entrance into this rectangle the bed of the 

 river is in an impassable box canyon and so continues to Cieneguilla. 

 Thence the canyon is still of great depth but permits of the passage 

 of a wagon road. In the formation of this narrow canyon it has 

 been necessary for the river to cut its channel through a wide-sweeping 

 lava flow of great thickness, a phenomenon that is re})eated at White 

 Rock canyon, 20 miles below. At La Joya the Espanola valley 

 opens out; this is 20 miles in length. 



