Las Capas Data Recovery

Aerial photograph of the Desert Archaeology field crew excavating within Locus B, Las Capas.

Purpose

Prior to the expansion of Pima County’s Tres Rios Wastewater Reclamation Facility, Desert Archaeology investigated a large Early Agricultural period irrigation community, where farmers lived and grew maize for several centuries from 1200 B.C. to 800 B.C. Multiple Desert Archaeology investigations at the site since the 1990s informed a robust research design with innovative analytical methods that produced groundbreaking results.

Actions

Records review to identify previously recorded cultural resources
Tested or excavated 3,455 of over 5,500 identified precontact features across 7 loci
Documented an extensive precontact canal system
Collaborated with University of Arizona bioarchaeologists to document and repatriate all ancestral remains.

Results

The site occupation was found to date primarily to the San Pedro phase of the Early Agricultural Period (1200-800 BC). Later, more sporadic occupation of the site extends from the Cienega phase (800 BC-AD 50) through the Hohokam and Protohistoric eras.
The project documented the oldest irrigated field system yet encountered in North America, consisting of a sequential network of canals and the hundreds of small bordered fields they watered, along with associated field houses and living areas.
An experimentally replicated agricultural plot allowed us to calculate the labor required to build and maintain the irrigated fields.
Coordinated bioarchaeological and lithic technology research demonstrated the presence of migrant populations from current-day Mexico in the Tucson Basin.
Geomorphological studies shed light on how the Santa Cruz River and its floodplain changed over time, and how human populations adapted to the changing landscape.
In 2009, Archaeology Magazine chose the Las Capas project as one of the ten most important discoveries worldwide.
In 2015, Desert Archaeology was recognized by the Shanghai Archaeology Forum for over a decade of research on the Early Agricultural period that culminated in the Las Capas project.

Date:

June 2015

Location:

Marana, Pima County, Arizona

Type:

Data Recovery

Compliance:

Local

Client:

Pima County

DAI Reports:

Anthropological Papers Nos. 50 and 51; Technical Report Nos. 2012-016, 2014-01, 2014-02, 2014-08, 2014-09, 2014-10

Services:

Data Recovery

Archaeological Reconstructions

Click any image below to enlarge.

A small cluster of San Pedro phase houses during excavation.

The Las Capas site contains the earliest agricultural fields yet discovered in North America. Our crew re-created a maize garden within an ancient field, using tools and technologies similar to those used 3,000 years ago. The main difference is that we used a hose, rather than the now-dry Santa Cruz River, to fill the canal.

Reconstruction of Las Capas, by Robert Ciaccio.

Phytoliths (preserved mineral linings of plant cells) from Las Capas: (a, b) maize; (c) bottle gourd; (d) cucurbita; (e) freshwater sponge, indicating a perennial flow in the Santa Cruz River; (f) modern Tohono O’odham bottle gourd reference (Photomicrographs by Chad L. Yost, University of Arizona).

The dark ash- and charcoal-stained sediment fire-cracked rock from a cleaned-out roasting pit show the shape of this San Pedro phase canal, and then subsequent layers of filling.

Quick Findings

In 2009, Archaeology Magazine chose the Las Capas project as one of the ten most important discoveries world-wide
In 2015, Desert Archaeology was recognized by the Shanghai Archaeology Forum

10+

Years of research on the period

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