Although Jackson made many photographs of the castles and towers of the Hovenweep, none of these were published in his reports, possibly because halftone methods of reproduction were then unknown. The illustrations that appear in the text of early reports are mainly reproductions of sketches. These reports, in which the discovery of the tower type of architecture and its adjacent cliff-dwellings were announced, should thus rightly rank as the first important steps in the scientific investigations of the stone-house builders of this district of our Southwest; although the allied “Casas Grandes” or great houses of the Chaco had been described a few years before by Gregg, Stimpson, and others.

We have, in addition to these pioneer reports, several magazine articles of about the same date, the material for which was largely drawn from them. One of the most important newspaper articles of that date was written by Mr. Ernest Ingersoll, published in the New York Tribune, and another, of anonymous authorship, is to be found in the Century Magazine for the year 1877. New forms of towers and castellated buildings were added in these accounts to those of the earlier authors.

One of the most important contributions to the antiquities of the region about Mesa Verde was made by the veteran ethnologist, Morgan, who published notes contributed by Mr. Mitchell on a cluster of mounds near his ranch. As no name was given this village it is here called the Mitchell Spring Village. Morgan likewise mentions the ruin at Mud Spring and a tower in the ruin near his spring. Professor Newberry was the first author to affix the name Surouaro to a ruin situated at the head of the Yellow Jacket Canyon.

Several of these ruins were described and figured by Mr. Warren K. Moorehead as “The Great Ruins of Upper McElmo Creek” in the Illustrated American for July 9, 1892, the sixth of a series of articles under a general title “In search of a Lost Race.” He gives descriptions of a “cave shelter” found near Twin Towers, Square Tower in “Ruin Canyon,” a building (Hovenweep Castle), and the tower at the junction of the North and South Forks of Ruin Canyon. This paper is accompanied by a map of Ruin Canyon by Mr. Cowen. In Moorehead’s discussion of these remains, individual towers and other ruins are designated by capital letters, A-V, to some of which are also affixed the names “Hollow Boulder,” “Twin Towers,” “Square Tower,” etc. Details of structure and measurements of the more striking buildings and a discussion of certain features of structure, some of which will be considered later under individual ruins, are likewise given.

The most important general article yet published on the prehistoric remains of the region here considered is by Dr. T. Mitchell Prudden,[4] who also mentions several of the ruins here treated. His most important contribution is a description of what he calls the “unit type,” which he recognized as a fundamental structural feature in the pueblos of this region. He also showed that the kiva in Montezuma Valley villages is identical with that of cliff-dwellings in the Mesa Verde, and emphasized, as an important feature, the union of the tower and the pueblo, a characteristic of the highest form of pueblo architecture.

Doctor Prudden has followed his comprehensive paper above mentioned with an account[5] of the excavation of one of the mounds at Mitchell Spring in which he adds to our knowledge of the structure of his “unit type.”

In “A Further Study of Prehistoric Small House Ruins in the San Juan Watershed,”[6] Doctor Prudden has furnished important additional data which shows the uniformity of the unit type over a large area of the San Juan drainage.

The following among other prehistoric remains in the district mentioned or described by Doctor Prudden are covered by the author’s reconnoissance:

The following towers can be identified from his figures:[7]