Dicke, Robert J. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XLIV (1955)
McCabe, Robert A.
The prehistoric engineer-farmers of Chihuahua, pp. 75-90 PDF (6.1 MB)
1955] McCabe—Engineer-Farmers of Chihuahua 85 the periphery. ' These stones were about the size of loaves of bread, partly buried and grown over in places with grass. This wagon wheel design was not easily discernible when walking near it, for I must have passed by or over it 25 times before seeing it in this fresh perspective. EARLY CHIHUAHUAN AGRICULTURE Studying and hunting game animals of ' this rugged back country left me little time for reflection on the archaic masonry that was seldom out of sight. This much, however, seems obvious: The dams were in some way associated with the pursuit of agriculture. ' The presence of pottery fragments in the ruins implies that the culture was archeologically recent and probably a cornbean-squash agriculture. Were these dams the precursor of mo'dern soil conservation practices and built to check soil erosion? Perhaps, but only as a secondary measure. The real reason, as stated earlier and also as expressed by others, was to catch and hold silt. Most of the country, including fairly level mesa tops, is extremely rocky and unsuited generally even to hand agriculture; the formation of soil from the flaky volcanic rock is reasonably fast and a check-dam along a run-off course would soon collect enough soil to support vegetation. Thus behind each trinchera arose a potential field. As the silt accumulated, a new tier of stones could be added to the dam. ' The water basin, or more properly soil basin, thus formed would mean additional land for the enlarging field. Seemingly in opposition :to this hypothesis is the fact that many of the dams were in places where there was little chance to catch or hold enough soil to make dam-building a worthwhile operation. Likewise there now exist slopes that would make very good fields if dammed, located near these almost negligible fields behind well-built dams. Those areas behind dams built on steep slopes and in narrow canyons are subject to periodic washing or side cutting during the rainy season. Thus it seems unlikely these were meant to be fields. It is difficult ' to guess what other function this type of dam may have served. If the deductions made thus far are correct, then the preconquest farmer of Chihuahua probably practiced soil conservation before he farmed much of his land. This has an ironic twist, since we came from a rich and "enlightened" land to the north where a small group of soil conservationists are trying to help an unwilling country prevent its soil, and indirectly its wealth, from flowing seaward.
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