Landscape Reconstruction in the Malpaso Valley, Zacatecas, Mexico

Description

Scientists around the world have observed grasslands turning into
deserts. How do human populations respond when this happens and to what
degree are they responsible? Because the process may take centuries,
even millennia, it is difficult to know. Archaeologists have the
potential to document the desertification of grasslands on a time scale
far grander than that of written history, and the Malpaso Valley,
Zacatecas, is a strategic place in which to do so.

Like several other valleys in northern Mexico region, it was occupied
for a few centuries by a large farming population only to be abandoned.
These valleys were a zone of frontier expansion and contraction for
Mesoamerican civilization; the main Malpaso Valley site, La Quemada,
dates to around A.D. 500-900. Our international, interdisciplinary
research group is evaluating environmental conditions before, during,
and after this occupation.

We are interested to learn whether the abandonment was associated with
a drying trend in the regional climate and whether there is evidence of
degradation of the environment by the ancient farmers. In addition to
the archaeological evidence excavated from the main site and
subordinate villages, we have made backhoe trenches in the Malpaso
River flood plain to collect sediments, pollen, phytoliths,
paleomagnetic samples, and radiocarbon samples. We have detected
changes in the streambeds indicating erosion and are using ancient
pollen and phytoliths to characterize vegetative cover.

These data allow us to reconstruct environmental conditions at
different points in time and evaluate hypotheses about the extent of
change, the human responses, and the human role in creating
disturbances that may have contributed to environmental changes.

Links

• Archaeological Investigations at La Quemada, Zacatecas, northern Mexico
• Connections and Impacts of Northern and West Mexican Cultures