Archaeological assessments are required when land to be developed has the potential to have archaeological resources or is known to have an archaeological site on it. In accordance with the Standards and Guidelines for Consultant Archaeologists (2011) developed by the Ontario Ministry of Culture, Tourism and Sport, archaeological assessment in Ontario takes place through a phased process as follows:
A Stage 1 assessment consists of archival examination of any historical, environmental and archaeological data for the study property. This information is then used to determine the archaeological potential of the property. Sources used for Stage 1 investigations include historical maps, land registry records, census rolls, oral histories, and Ministry of Tourism, Culture and Sport site data files. Areas that are identified as having moderate to high archaeological potential require further archaeological investigation in the Stage 2 assessment.
Stage 2 investigations consist of a field survey to identify any archaeological resources on the proposed land development property and to determine if any may be of potential significance. Where ploughing is possible, fields will be walked in 5 m intervals looking for artifacts on the surface. In areas that cannot be ploughed, such as forested and overgrown pasture areas subsurface testing will occur, which consists of hand excavated test pits at 5 m intervals. The archaeologist will then determine whether any archaeological resources found are of sufficient cultural heritage value to require a Stage 3 assessment. If nothing is found, a report is made to the Ministry of Culture, Tourism and Sport and the property will be cleared for development.
Stage 3 archaeological assessments are triggered when a potentially culturally significant archaeological site was encountered during the Stage two investigation. This requires additional excavation of the site in order to determine the extent of the site and evaluate its cultural heritage value or interest. For a site located on a ploughed field, a controlled surface pickup is conducted, in which all surface artifacts are individually plotted. The deposit is subjected to a series of test excavations to determine its age, cultural affiliation, density, and extent. In forests, overgrown pasture areas or any other places cannot be ploughed, the archaeologist maps the limits of a site and acquires further information about the site's characteristics by excavating one-meter by one-meter test units across the site. Stage 4 assessments are recommended for sites that demonstrate significant cultural heritage value as determined by the Ministry’s Standards and Guidelines.
Stage 4 assessments include implementing long-term protection strategies for the archaeological site, while development proceeds around it. A site which is endangered and cannot be preserved is subjected to mitigative excavation, which involves documenting and removing the archaeological site through large-scale excavation, prior to the development of the site.