6. San Francisco River district.
Following is a brief memorandum showing the extent of each district:
I. RIO GRANDE BASIN.
This culture area, lying wholly in New Mexico, embraces the Rio Grande Valley with its tributaries from Ojo Caliente on the north to Socorro on the south and from Acoma on the west to the plains east of the Manzano Mountains.
II. SAN JUAN BASIN.
The ruins of the San Juan Basin consist of both large and small communal houses and true cliff dwellings in great numbers. They are scattered in numerous, irregular groups over the contiguous portions of New Mexico, Colorado, Utah, and Arizona. All the ruins of the San Juan and its tributaries have suffered much from destructive collectors.
III. LITTLE COLORADO BASIN.
This extensive region embraced in the valley of the Little Colorado and its tributaries is pre-eminently a region of pueblo ruins, though some cave dwellings are found. It is especially rich in prehistoric pottery. Because of its wealth of relics this region has suffered more than any other from the traffic in prehistoric wares. However, we are fortunate in that Dr. J. Walter Fewkes of the Bureau of American Ethnology has made the districts of the Little Colorado a subject of research for many years. His voluminous reports on this region have put us in possession of a vast amount of information on the archæology and ethnology of the Southwest. His collections from Sikyatki for the National Museum, made in 1895, with the assistance of Mr. F. W. Hodge of the Smithsonian Institution, together with the collections made from the Holbrook district by Doctors Fewkes and Hough, form, probably, the most valuable collection of prehistoric pottery in existence. Another extensive collection of pottery from this region may be seen in the Field Columbian Museum in Chicago.
IV. GILA BASIN.
This is another region that embraces practically every species of prehistoric ruins. It is of vast extent and comprises, besides the valley of the Gila proper, the large valleys of the Salt and Verde rivers. As a seat of prehistoric culture it was one of the most extensive and populous. Many ruins of these three great valleys are on irrigable lands, and, accordingly, have disappeared with the advancement of agriculture.