The Construction and Configuration of Anasazi Pebble-Mulch Gardens in the Northern Rio Grande

Rio Grande Anasazi in the fourteenth and fifteenth centuries A.D. mulched hundreds of garden-sized plots with pebbles to increase soil moisture, reduce erosion, extend the growing season, and increase crop yields. This paper reports on the construction and configuration of pebble-mulch gardens in New Mexico, focusing particularly on those in the Galisteo Basin. Surfaces adjacent to these gardens were scraped and pits were excavated to collect gravel, which was placed over garden surfaces in layers 5 to 11 cm thick. Gardens averaged 15 x 23 m in size, although both size and shape were highly variable, and they collectively covered an area of 41,000 m2 Although this unique agricultural strategy has been shown to be effective, construction was limited to sites with natural gravel deposits, pebbled surfaces inhibited the recycling of crop wastes, and such gardens never became as widely used as more traditional field forms.

Nelson's Stratigraphy

The immediate stimulus for N. C. Nelson's stratigraphic technique in the Galisteo Basin, New Mexico, was his participation in 1913 in Obermeier and Breuil's excavations in Castillo Cave, one of the most famous of the Spanish paleolithic sites.

Nels C. Nelson and Chronological Archaeology

A series of papers at the 24th Annual Meeting of the Society for American Archaeology, in Salt Lake City in 1959, was devoted to Developments in Dating Techniques, and dedicated to Nels C. Nelson in recognition of his pioneering role in establishing the technique of stratigraphic excavation in America. During his work in the Galisteo Basin of New Mexico in 1914 he dug a series of ten 1-foot levels, classified all the sherds found in them into seven types, and calculated their frequencies by levels. These resembled sections of normal distribution curves, and demonstrated that statistical analysis of data from arbitrary levels could reveal chronological change just as could data from physically distinct strata. Within a few years this technique was employed by several other archaeologists and it continues to the present to be an indispensable technique of investigation.