New Mexico Geological Society Annual Spring Meeting — Abstracts

El Camino Real was a 1,600 mile long trade route between Mexico and San Juan Pueblo, New Mexico between 1598 and 1882. It is commonly thought that the Jornada Del Muerto, located in southern New Mexico, was one of the most feared sections along the El Camino Real primarily due to the scarcity of water.  Archaeologists have hypothesized that water availability largely influenced the travel route and locations of parajes (campsites) in the Jornada Del Muerto. In an effort to address this hypothesis, the main objective of this study is to assess spatial and temporal variability of water availability to travelers traversing the Jornada Del Muerto.

The Jornada Del Muerto, within the study area, is structurally characterized as a south plunging syncline bounded by the Caballo Mountains to the west and the San Andres Mountains to the east.  The north-south trending Jornada Draw fault zone bisects the syncline, resulting in the exposure of Cretaceous and early Paleogene sandstones, sitstones and conglomerates on the west side of the study area.  Water levels, isotopic and geochemical data indicate the presence of a shallow perched aquifer system in these rocks.  This perched system is characterized by depths to water ranging from 180 feet to less than 20 feet below the surface.  According to tritium concentrations, this shallow groundwater is composed of a mixture of modern water (<10 years old) and older water.  This groundwater system responds quickly to wet and dry periods on the order of years to decades. This shallow system does not appear to be present east of the fault zone, where groundwater is significantly deeper (>200 feet) and older according to tritium analyses.  Ojo Del Muerto spring, located at the northern boundary of the study area and on the west side on the surface water divide in the lower Rio Grande Basin, exhibits an apparent carbon-14 age of over 11,000 years before present, and therefore likely discharges water from a regional groundwater system which is less responsive to annual and decadal precipitation patterns.

Shallow water sources that were potentially available to El Camino Real travelers include seeps, springs, and playas.  Simple hydrologic models were used to evaluate these water sources in terms of quantity and reliability.  Ojo Del Muerto spring is likely the most reliable water source and produces enough water to support a medium sized group of up to 250 people and several hundred livestock. Playas undoubtedly supply the largest quantity of water, which could support large groups of up to 500 people and several thousand livestock.  However, the occurrence of water in these playas is highly variable and therefore playas are a less reliable source.  Seeps and local springs located in drainages produce significantly less water, but are more reliable than the playas.  The two northern-most parajes in the study area are located near several of these water sources.  Study results also have many implications for strategies used to navigate the Jornada Del Muerto.