GEOLOGIC MAPPING ALONG THE SOUTHERN BORDER IN ARIZONA: AVOIDING AND MANAGING CLOSE ENCOUNTERS

For the past several years, we have been mapping the surficial geology and investigating surface processes and related hazards in Organ Pipe Cactus National Monument (ORPI) on the U.S.-Mexico border, for use in park resource assessments and management. Conducting geologic investigations along the border presents interesting challenges. ORPI includes one of only two N-S paved roads that access the U.S.-Mexico border in the sparsely populated 400 km between the Yuma and Tucson. Thus, it is a significant corridor for legal and illegal border traffic. The 50-km-long southern margin of ORPI is relatively permeable. A 5-m-high solid metal fence has been erected recently along the border for 3 km on either side of the official border crossing, with a combination of barbed wire fence and vehicle barricades along the rest of the ORPI boundary. Evidence of undocumented aliens (UDAs) is common, including trash, foot trails, and occasionally vehicle tracks. Nearly all of ORPI is designated as wilderness, so road access is very limited and long hikes are required to investigate some field relationships. About 40% of ORPI is accessible to researchers only with armed escorts because of drug trafficking. U.S. Border Patrol activity is ubiquitous on the roads, and occasionally agents have been encountered in the field.

We have worked closely with ORPI staff in order to safely conduct our research. Our map area is limited almost entirely to the publicly accessible part of ORPI. At the beginning of each field period we meet with ORPI staff to discuss mapping areas and active trafficking corridors, and obtain field radios. Mapping teams consist of 2 persons who remain in visual contact at all times. Basic field procedures include using sight, hearing and smell to avoid UDAs, entering heavily vegetated areas or gullies with caution, giving regular status updates to ORPI staff via radio, and leaving the field by 5 pm. We have not been armed, but have commonly carried pepper spray. We take every opportunity to inform Border Patrol agents about our activities and locations. ORPI staff arranged for contract security guards to accompany AZGS geologists for several days when mapping in “closed” areas. We have observed UDAs from a distance several times, but thus far have been able to avoid threatening situations by following these procedures.