The science of archeology has contributed to our knowledge some of the most fascinating chapters in culture history, for it has brought to light, from the night of the past, periods of human development hitherto unrecorded. As the paleontologist through his method has revealed faunas whose like were formerly unknown to the naturalist, the archeologist by the use of the same method of research has resurrected extinct phases of culture that have attained a high development and declined before recorded history began. No achievements in American anthropology are more striking than those that, from a study of human buildings and artifacts antedating the historic period, reveal the existence of an advanced prehistoric culture of man in America.

The evidences of a phase of culture that had developed and was on the decline before the interior of North America was explored by Europeans are nowhere better shown than in southwestern Colorado, New Mexico, Arizona, and Utah, the domain of the Cliff-dwellers, or the cradle of the Pueblos. There flourished on what is now called the Mesa Verde National Park, in prehistoric times, a characteristic culture unlike that of any region in the United States. This culture reached its apogee and declined before the historic epoch, but did not perish before it had left an influence extending over a wide territory, which persisted into modern times. Through the researches of archeologists the nature of this culture is now emerging into full view; but much material yet remains awaiting investigation before it can be adequately understood. The purpose of this article is to call attention to new observations bearing upon its interpretation made by the author, under the auspices of the Bureau of American Ethnology, on brief trips to Colorado and Utah in 1917 and 1918.

The peculiar cliff-dwellings and open-air villages of the Mesa Verde are here shown to be typical of those found over a region many miles in extent. They indicate a distinct culture area, which is easily distinguished from others where similar buildings do not exist, but not as readily separated from that of adjacent regions where the buildings are superficially similar but structurally different. In order to distinguish it from its neighbors and determine its horizon, we must become familiar with certain architectural characteristics. As our knowledge of the character of buildings in this area is incomplete, the intention of the author is to define the several different types of buildings that characterize it.

When, in 1915, there was brought to light on the Mesa Verde National Park, Colorado, the mysterious structure, Sun Temple, the author recalled well-known descriptions of towers and other related buildings that have been recorded from other localities in southwestern Colorado and Utah. The published descriptions of these structures did not seem to him adequate for comparisons, and he planned an examination of these great houses and towers, hoping to gather new data that would shed some light on his interpretation of Sun Temple. During the field work in 1917, thanks to an allotment from the Bureau of American Ethnology for that purpose, he undertook a reconnoissance in the McElmo district, where similar buildings are found and where he believed cultural relatives of the former inhabitants of Mesa Verde once lived. In 1918 he extended his field work still farther. He investigated ruins as far as the western tributaries of the Yellow Jacket Canyon, penetrating a short distance beyond the Colorado border into Utah. The object of the following pages is to make known the more important results of this visit, and interpret the evidence they present as a contribution to our knowledge of the extension in prehistoric times of the Mesa Verde culture area.