Alan P. Sullivan III

Figure 1. View of several hundred square kilometers of densely forested terrain along the eastern South Rim of Grand Canyon. Beneath this canopy are thousands of archaeological sites whose locations and characteristics are largely unknown to resource managers and scientists. This “hidden heritage” problem affects all units in the National Park System with significant human histories that are registered by highly variable concentrations of surface archaeological phenomena.

Draped like emerald-green bunting over the northeastern corner of the Coconino Plateau in north-central Arizona, the ancient coniferous forest that mantles Grand Canyon National Park and the adjoining Kaibab National Forest (fig. 1) camouflages thousands of archaeological sites. Bypassed by millions of visitors annually are hundreds of square kilometers of de facto wilderness, terrain that is rarely seen or traversed by humans though not congressionally designated as wilderness. Yet the area’s abundant hidden heritage creates a number of problems for resource managers and researchers alike. (Heritage resources are by-products of prehistoric and historic human activities such as ruins, hearths, and artifacts that are potentially significant to various cultural groups.) First, without accurate knowledge of the regional distribution of heritage resources, managers are constrained in their decision making, particularly in responding to “stressor” syndromes (e.g., population growth, resource extraction, encroaching development) that affect visitor experiences (Bishop et al. 2011). Second, critical ground-disturbing projects, often intended for public safety (e.g., road widening) or experience enhancement (e.g., visitor services expansion), are delayed or become needlessly intrusive because even coarse-grained data, such as the presence or absence of heritage resources, are chronically unavailable in considering alternative land-modification options (Ahlstrom et al. 1993). Third, scientific projects related to understanding the human and natural histories of parks and surrounding areas are disadvantaged because regional-scale information is discontinuous and the significance of known data points is incompletely understood because of erratic sampling (Sullivan et al. 2007).

Here, we share the results of recent applications of remote sensing that show great potential for helping managers and scientists overcome the aforementioned problems from two different information settings. In some cases, prior knowledge is available about the surface archaeology of heritage resources that may be affected by a surface-modifying project, yet the information required to make an informed judgment regarding their disposition (e.g., preservation or long-term monitoring) is unavailable without additional, often expensive and time-consuming, archaeological excavation (Anderson and Neff 2011). Moreover, in most cases, no information is available whatsoever about the surface archaeology of heritage resources that may be threatened by park projects, visitor impacts, or operations of adjacent federal agencies (Fairley 2005). We intend to illustrate that remote sensing holds great promise in helping park managers—regardless of park size or annual number of visitors—meet their obligations within the letter and spirit of the Wilderness Act, as well as other federal heritage laws (e.g., National Historic Preservation Act). Our message is straightforward as well: current gaps in understanding the extent of the “hidden heritage” problem can be resolved with the broad and consistent application of the methods we discuss, which we believe ought to play a larger role in long-term management of and research planning for all units in the National Park System.¹