Isolates

The value of formally recording isolated prehistoric archaeological finds within the California Historical Resources Information System (CHRIS) has been both challenged and defended. Isolates have been variously defined on the basis of the number of surface artifacts encountered (e.g., a single artifact, three related artifacts, etc.) and their separation from other archaeological remains (e.g., absence of additional material within a certain radius, a certain maximum density of artifacts). A consensus exists that there is value in documenting, collecting, and curating some highly unusual isolates, such as rare types of projectile points (fluted, etc.), decorated exotic potsherds, and artifacts made from regionally exotic lithic material types. However, there is no consensus as to whether routinely recording common types of artifacts serves a legitimate research purpose.

Artifacts, including isolates, attest to types of prehistoric activity at the locations where they ae encountered. The issue is whether information on the occurrence of isolates is useful. One study made use of a geographic information system (GIS) database of records for 1,362 prehistoric archaeological sites and 194 isolates in southeastern San Diego County (Schaefer and Laylander 2014). The environmental contexts of isolates within previously surveyed areas was compared with the contexts of 1,378 systematic sample points within those areas. Significant differences between the isolate locations and the sample points were not identified, suggesting that information on isolate distributions may constitute essentially random “noise,” from a perspective of discovering and interpreting land use patterns.

PROSPECTS

Additional GIS-based analyses of recorded isolates may be successful in identifying interpretively significant patterns in isolate distributions, or the analyses may confirm isolates’ ubiquity and their lack of interpretive value.