From here I made an excursion to an ancient pueblo site. As usual, there were traces of small dwellings, huts of undressed stone, and fragments of pottery. We found three mortars and one pestle, a remarkable number of metates (the stone on which corn is ground), and the corresponding grinding stones, showing that a large population must have once lived here, huddled together in a small space.
Ancient pecking on a trachyte boulder one foot square.
But the most striking feature of antiquity met thus far on our journey were curious stone terraces built across the small gullies. They are called trincheras (trenches). Some of them do not appear to be very old, and many present the appearance of tumble-down walls, but the stones of which they are constructed were plainly used in their natural state. Although many of the boulders are huge and irregular in shape, they were used just as they were found. The building material always conformed to the surroundings: in places where conglomerate containing water-worn boulders abounded, this was used; where porphyry was prevalent, blocks of that material were employed. There is no trace of dressing or cutting, but in the mason work considerable skill is evident. The walls are not vertical, but incline somewhat toward the slope on which they are erected. The terrace thus formed is often filled with soil to the height of the wall-top for a space of from fifteen to twenty feet. Earth taken from them does not show any colours. Some of these trincheras measure thirty feet in length by four feet in height, while the smallest ones I saw were only five feet long and three feet high. Naturally enough, the largest ones are in the lower part of the gullies; then, some twenty-five feet back and above, others almost as large may be found. As the arroyo rises and narrows, the walls, each placed a little higher up the slope than the preceding one, are necessarily smaller.
In the mountains near Nacori, especially on their eastern and southeastern sides, trincheras were encountered in every gulch as high up as six thousand feet, though steep crests and the mountain tops bear no traces of them. In one arroyo, which was about a thousand feet in length and of comparatively gentle slope, twenty-nine trincheras were counted from the bed of the main drainage to the summit of the mountain. Some of them were quite close together, three being within eighteen feet of one another.
These trincheras somewhat resemble the small terrace gardens of the Moqui Indians, and have undoubtedly been used for agricultural purposes, just as they are used by the Tarahumares to this day ([page 152]). It is true that they are built in great numbers, sometimes in localities that would appear unsuitable for farming; but, on the other hand, they are seldom, if ever, found far from the remains of habitations, a fact from which it may also reasonably be inferred that the ruined houses, as well as the trincheras, were originally built by the same race. Some of the terraces were, no doubt, erected as a protection of the crop against enemies and wild animals; but it is impossible to think that they were intended for irrigation dams, though we did see water running through some, coming out of a marsh. Still less likely is it that they had been used as mining dams.
As soon as the plains of Northern Sonora were left behind, and the country became hilly and broken, these peculiar structures were conspicuous. At first they appeared more like walls built simply along the slopes of the hills, and not crossing gulches. They seem to be more numerous in the western and central part of the sierra, its spurs and foot-hills, than in the eastern part of the great range. As regards their southern extent, they are not found further south than the middle part of the state of Chihuahua. Captain Bourke, in his book, “An Apache Campaign,” mentions that “in every sheltered spot could be discerned ruins, buildings, walls, and dams, erected by an extinct race once possessing these regions.” Mr. A. F. Bandelier, on his journey to the Upper Yaqui River, in 1885, which took him as far as Nacori, also refers to them, and Professor W. J. McGee, on his expedition in 1895, found in Northeastern Sonora ruins locally known as Las Trincheras, which he considered the most elaborate prehistoric work known to exist in Northwestern Mexico. They comprise, he says, terraces, stone-walls, and inclosed fortifications, built of loose stones and nearly surrounding two buttes.
I must not omit to mention that in a week’s exploration in the mountains near Nacori, Mr. Stephen and his party did not find any pottery fragments, nor flint flakes, nor grinding stones. They reported that there was in that region no other trace of an early people than the hundreds of trincheras in the lower portions of the arroyos.
Noteworthy, however, was the frequent occurrence of old trails across the hills, some quite plainly traceable for three and four hundred yards. Old oaks stretched their limbs across many of them quite close to the ground.
While at Nacori I learned from the inhabitants that at no great distance from their town there were several deposits containing huesos giganteos (giants’ bones), a name given to fossils in this part of the world, where the people imagine that the large bones were originally those of giants. I had then neither time nor men to make excavations of any importance; but Mr. White, the mineralogist of the expedition, whom I sent to look into the matter, and who devoted a week to the examination of the deposits, reported that one of them, in a valley sixteen miles south of Nacori, was a bed of clay thirty feet thick and about a mile and a half long. On the edge of this field he discovered a tusk six feet eight inches long and twenty-six inches at its widest circumference, and having almost the curve of a circle. It was not petrified and had no bone core, but the hole filled in with clay, and its colour was a rich mahogany. It was undoubtedly the tusk of a mammoth.