PREFACE

As with the selection of sites, the excavation strategy employed for data recovery is driven by the datarequirements of the research design and the nature and condition of the site being investigated. Thepriority given to the recovery of chronological and subsistence data mandates an emphasis on theinvestigation of features where organic materials are most likely to be preserved. Similarly, the prioritygiven to acquiring settlement (site-structure) data and the need to recover large artifact assemblagesdictate areally-extensive excavations and, with some exceptions, the investigation of entire sites. Howthese general approaches are applied varies with the class of sites. For southeastern New Mexico, therelevant classes are caves and rockshelters, sites with substantial architecture, and open sites.Caves and Rockshelters(Cave and Rockshelter Component Types)Caves and rockshelters provide a protected or partially protected depositional environment that potentiallycontains stratified cultural deposits and in which organic materials are more likely to be preserved. Theexcavation strategy for these sites therefore emphasizes vertical exposures and the recovery of subsistencedata. Prior to any excavations, a 1 by 1 m grid system and an elevation datum should be established at thesite, encompassing both the sheltered area and the open area immediately fronting the shelter opening orcave mouth. Typically, the elevation datum is permanently marked at a convenient point on the cave orshelter wall. The site is then mapped. Maps should include both a plan and profiles of the shelter or caveand a finely scaled topographic map of the modern ground surface.Most cave and shelter sites in southeastern New Mexico have been vandalized, so after mapping, the firststep in the excavation is often to clear the spoil dirt from the excavation area and to face up any looter’spits. Screening the spoil dirt may recover substantial materials, albeit of uncertain provenience, andexamination of the looter’s pits may be useful in discerning the site stratigraphy. After clearing anylooter’s spoil or initially if the site is undisturbed, one or more trenches should be dug across the drip lineand into the shelter interior. Excavations should be dug in 1 m grid units and natural stratigraphic levelsif at all possible or 10 cm arbitrary levels oriented on the same plane as the modern ground surface. Allexcavated sediments should be screened through 1/8 in mesh hardware cloth. Any features encounteredduring the excavation of the trench(es) that extend into adjacent units may be pedestalled if they do notinterfere with exposure of the profile. Once the trenching is completed, the trench walls should becarefully examined, preferably by a geomorphologist or geoarchaeologist, to define and describe the sitestratigraphy. Trench walls should be thoroughly documented using a combination of narrativedescription, profile drawings, and photographs. If deposits in the cave or shelter are much more than 1 mdeep, the trench walls will either have to be shored in accordance with OSHA guidelines or theexcavation will have to be “stepped back,” expanding the trench width. This will require that theexcavator maintain one or more “floating profiles” to document the site stratigraphy, which requiresparticularly careful attention to elevation controls.Once the site stratigraphy is established, the emphasis shifts to horizontal exposure of the successiveoccupation levels. Ideally, this will be a top-down process, beginning with the uppermost occupationlevel and working downward through the deposits. Excavations are expanded outward from the trenchwall following the natural stratigraphic units to expose the occupation surface and any associated features,including any refuse deposits or work areas on open areas and slopes beyond the shelter or cave. Thisideal is rarely achievable. Strata may pinch out or be interrupted by aboriginal excavation or animalburrowing, or the sediments may be thoroughly mixed by burrowing rodents and other pedo-turbationprocesses. Excavation areas might be blocked by outcropping bedrock, rock-falls, or features originatingat higher levels, or the need to stair-step excavations in deep deposits will preclude the full exposure ofthe entire occupation surface. All of these potential impediments emphasize the need to maintain carefulthree-dimensional provenience controls for all excavated sediments and to continually update maps andprofiles for each excavation units as well as master maps for each occupation surface.6-2