Archaeological Survey and Methodology

Archaeological Survey and Methodology Visual Inspection/ Visual Pedestrian Survey When field conditions warrant, systematic visual inspection of plowed fields and surface collection of artifacts has proven to be a highly effective and efficient method of site survey. Systematic surface collection is encouraged after re-plowing and disking of previously plowed fields to a depth no greater than the previous disturbance prior to inspection. However, even in previously plowed areas, the clearing of trees and large brush to facilitate surface collection has the strong potential to disturb sub-plowzone soils and, therefore, is not regarded as an acceptable methodology. All exposed surfaces are to be inspected. If an area has greater than 50% surface visibility but is in a dynamic depositional environment (e.g., the foot of a slope or adjacent to an aggrading waterway) or the scope of work includes substantial/significant sub-plowzone disturbance, then 30-m (~100-ft.) interval subsurface testing is required. Highly eroded areas, where subsoil is visible at or just below the surface, as well as recently plowed fields are the most common instances where such high visibility exists. The archaeologists’ judgment concerning visibility is especially critical in fallow or dry fields, where close-interval (30 m) subsurface testing will be necessary. In general, pedestrian survey will be systematic in coverage, with the maximum interval between surveyors not exceeding 30 m. Surface visibility and topography alone do not sufficiently define a site. When an archaeological site is identified by visual inspection alone, excavation of at least two shovel test pits (STPs) is needed to assess site depth and the presence or absence of intact cultural strata and/or feature, and assist in boundary delineation. However, low probability areas (for example, poorly drained soils and steep slopes, generally with a grade greater than 15%) and extensively disturbed (for example, previously subjected to land-leveling, clearing and grubbing activities, and other similar earthmoving activities) non-floodplain areas need only be subjected to visual inspection. If the visual survey locates natural benches, quarries, or other cultural features, the visual testing is to be augmented with additional, selectively or judgmentally placed, STPs. Surface Collection At the survey level, a complete surface artifact collection should not normally be made unless the site contains few artifacts or shows evidence of previous and/or active looting or vandalism. If a surface collection is made, an appropriate sampling method should be utilized and based on the investigator’s assessment of field conditions as well as the type and density of artifacts present. An investigator’s collection strategy should be specified in field notes, for example: all diagnostics and a representative sample of other observable materials, or controlled and repeatable samples of every surface artifact in designated locations, or a minimum number of each type of historic ceramic and glass plus other diagnostic items, etc. Surface collection is not a valid survey strategy on sites where ground visibility is less than 50%. Surface visibility and topography alone do not sufficiently define a site. Although a surface collection may help to define horizontal site limits, it should be supplemented with more traditional subsurface testing, particularly when surface visibility is discontinuous or variable. Subsurface testing also provides information about stratigraphy, the vertical distribution of material, and site integrity which cannot be obtained from pedestrian survey data alone. Subsurface Survey Although a surface collection may help to define horizontal site limits, it must be supplemented with subsurface testing, particularly when surface visibility is discontinuous or variable. Subsurface testing also provides information about stratigraphy, the vertical distribution of material, and site integrity, which cannot be obtained from visual survey alone and is necessary to establish the extent of a site even when surface visibility is unrestricted, and topographic changes indicate a possible boundary. Excavation of STPs (Shovel Test Pits, square in profile and not smaller than 12 inches [30 cm] in width) remains one of the most reliable means of site identification in areas of low surface visibility. Whenever possible, STPs are to be tied to a known datum or fixed reference point, with their location clearly marked on appropriate maps. As a general rule, STPs are to be excavated at intervals no greater than 30 m and will continue to culturally sterile subsoil, if possible. Thirty-meter interval shovel tests can be used to establish the general boundaries, with two consecutive negative shovel tests establishing the edge of the site. Thus, the interval between two distinct sites will be at least 60 m (197 ft.). Different site types, as well as soils and topography, may justify differing STP intervals. A shorter/tighter interval is recommended if small, low-density sites are encountered. Shorter intervals may be utilized after consultation with and approval from MDAH archaeology staff. The standard 30-m interval for STPs may also be augmented by judgmental testing in high probability areas such as promising landforms or areas containing vegetation or cultural landscape features associated with known or suspected sites locations. Archaeological site boundaries are to be established by excavating radial shovel tests in no less than four directions. When these resources are identified, it is recommended that the consultant implement a close-interval (5-10 m [16-33 ft.]) shovel-testing strategy to delineate both the horizontal and vertical boundaries of the resources within the survey area. Close interval shovel testing should be continued within the survey area until two sequential negative tests are completed. This may be achieved through the use of a cruciform delineation (i.e. in all four directions from a site datum) or grid strategy as long as the spacing of between 5 and 10 m is maintained to establish site boundaries. Additionally, 5-10 m intervals should be excavated to determine whether individual artifacts recovered from lone or single STPs with no adjacent positive STPs represent isolated finds or small low-density sites. All soils from STPs must be screened through ¼-inch hardware cloth. All artifacts fifty years of age and over are to be retained with the exception of materials such as brick, shell, charcoal, etc., which may be quantified in the field, a sample retained, and the remainder discarded. Shovel tests are to be excavated to a depth of at least 70 to 80 cmbs (centimeters below surface) (2.3 to 2.6 ft.) or until impenetrable substrate (i.e., bedrock or clay), known culturally sterile subsoil, or the water table is reached (see 6.4. Special Environment Surveys). If excavation exceeds this depth, an auger or Oakfield soil probe should be employed from the base of shovel test excavation to a maximum depth of 120 cmbs (3.94 ft.). Notes on all STPs and trenches will be recorded and are to include information on survey/site/transect identification and location, with a representative profile drawing or detailed description of strata, soil types, Munsell descriptions, depth measurements, and a listing of artifacts (both kept and discarded). Note the environmental conditions under which any testing strategy was employed (for example, adverse weather, condition of ground surface, etc.). A detailed map is to be prepared showing areas surveyed, areas eliminated from survey due to disturbance, slope, wetness, etc., and the location of the positive and negative STPs. Remote Sensing Remote sensing should be used to augment more traditional survey methods by identifying high potential areas for subsurface testing. Remote sensing (using metal detectors, proton magnetometers, ground penetrating radar, etc.) is recommended for sites associated with the Contact Period or Civil War, and is particularly useful for identifying burials. In underwater survey, remote sensing is often effective in identifying targets for later diver verification. A specific case is to be made in the research design for the use of remote sensing and its relationship to other survey methods made explicit. Four geophysical techniques are principally employed in archaeology: magnetometry, electrical resistivity, electromagnetic conductivity (EM), and ground-penetrating radar (GPR). For a discussion of each approach, their suitability in various environments, and the latest advances in the field of geophysical methods (see Geophysical Surveys as Landscape Archaeology by Kenneth L. Kvamme). Ruler 12.6.4. Special Environment Surveys Deep Sediments If colluvial, alluvial, or aeolian deposits are known to be present in the survey area from background research or by field inspection, testing will be needed to identify buried sites or the potential for such sites. This may be accomplished through a combination of methods such as coring, hand excavation of deep shovel tests, or mechanical slit trenching. The choice of technique will depend upon the depth of the deposits. If limited to shovel test excavations exceeding 70 to 80 cmbs in depth, an auger or Oakfield soil probe should be employed from the base of shovel test excavation to a maximum depth of 120 cmbs (3.9 ft.). MDAH strongly recommends that deep testing be performed on all parcels of alluvial or colluvial soil within the project area, especially for projects with deep vertical impacts. If full-scale systematic testing of the project area is not feasible, a geomorphologist is to be employed to develop a sampling program that identifies soils suitable for the preservation or formation of cultural deposits. When deep testing is accomplished by the use of mechanical equipment, care must be taken to avoid excessive damage to fragile archaeological sites. Slit trenching with heavy equipment such as a backhoe (preferably toothless) is to be used in situations where deep sediments cannot be reached through hand excavation. Trenches are to be placed in a manner suitable to reconstruct the past and present landforms. For large continuous sections of terrain, the testing is to be adequate to reconstruct the alluvial history of the floodplain. The excavations are to continue until a depositional environment not favorable for formation or preservation of cultural horizons is found. In special circumstances where the terrain limits the access of heavy equipment and hand excavation is not feasible, coring or auguring may be implemented. The soils from the cores are to be extracted in a controlled manner and sifted when appropriate. After excavation, the trench profile will be troweled to inspect for stratigraphy and cultural features. A detailed profile drawing and description shall be completed. If a geomorphologist is used, he or she is to assist in the placement of trenches, evaluation, and interpretation of the excavation profiles. The evaluation may include tests for soil type and texture, standardized color descriptions, and grain size distributions. The geomorphologist will submit a detailed interpretive analysis on the deep testing that will be included as an appendix to the full technical report of investigations. This analysis will address the issues of site depositional processes, their effects on archaeological preservation, visibility of archaeological sites, and landform evolution over time. A summary and discussion of the results should be presented in the body of the technical report. In most cases it will not be possible to determine if buried cultural artifacts are present simply by visual inspection of the profile alone. Therefore, hand excavation will be required. Preferably, a three-foot-square test unit will be excavated at the margin of each backhoe trench where favorable soil horizons have been identified. The test unit will be excavated in a series of arbitrary and/or natural stratigraphic levels until soil horizons not favorable to the formation or preservation of cultural horizons have been identified. All soil will be sifted through ¼-inch mesh hardware cloth and the artifacts retained according to level. As conditions dictate, alternate sampling strategies may be implemented to evaluate the integrity, age, and cultural period of the soil profile. For example, in consultation with the geomorphologist, recent fill layers or very recent alluvium may be removed without sifting. However, the researcher must justify that the sampling strategy is satisfactory to identify historic resources that may be present. In addition, if cultural material is encountered during deep testing and a geomorphologist is not already employed, arrangements are to be made to use a geomorphologist in an evaluation of all the trenches. Urban Sites An urban property is defined as any lot within the boundaries of a platted city block within an incorporated city, village, or town. Investigators are strongly encouraged to discuss urban survey strategies with MDAH as the research proposal is developed. Deviations from these standards can be agreed upon prior to beginning fieldwork and described in the report. Any deviations developed in the field, and their rationale, must be described in the report. Prior documentary research is critical because the spatial limits of urban archaeological deposits often cannot be defined in the same manner as the boundaries of non-urban sites. Such research may aid in determining the historical boundaries of streets, blocks, house lots, etc. Given the unique nature of these settings, the typical 30-m grid system nor traditional site delineation techniques are sufficient for defining site boundaries. Each lot is considered by MDAH to be a separated entity, inherently defined by its legal boundary. Therefore the typical approach of two negative shovel tests defining the edge of an archaeological site is not required nor necessarily applicable. Consequently, the definition of the site boundary should be restricted to the current or historic, legally-defined limits of the lot. This can be depicted through historic Sanborn maps, city maps, historic and modern aerial photographs, physical separation of lots from neighbors through the use of fences and plantings along lot lines, etc. Each urban lot should be subjected to survey to see if archaeological deposits are present. (For further information about urban sites and developing boundaries for urban districts please see NRHP Bulletin #21). In general, identification efforts in an urban area are to include: 1. STPs excavated at 10m (33 ft.) intervals on transects spaced no further than 10m apart; 2. All STPs should be square in profile, at least 30 cm (~1.0 ft.) in width, and be excavated to sterile subsoil or a minimum depth of 80 cmbs (2.6 ft.); 3. Identification of the presence, distribution, and preservation of architectural evidence, site stratigraphy, features, and assessment of site significance based upon all available documentary evidence. Previous work at urban sites regionally indicates it is useful to target mid-lot and backlot areas for cellars, privies, wells and cisterns; 4. Recordation and assessment of features containing large numbers of artifacts; 5. The use of metal detectors is encouraged along 1.5-m (~5.0 ft.) lanes along transects spaced no more than 10 m apart; 6. Sampling strategies for artifact recovery. Sampling strategies are to be addressed on an individual basis and the method chosen justified in the research design; 7. Recordation of excavation procedures including drawings and photographs; and 8. Geophysics may be used on vacant lots where traditional survey methods can be employed (i.e. paved lots, etc.). In cases where the above techniques are not applicable, please consult MDAH about alternative survey strategies/methods. Military Sites Conventional survey employing shovel testing at military sites has consistently proven to be unsuccessful in identifying these types of sites across the Southeast. Military sites such as encampments and battlefields are to be considered sensitive resources as many contain unmarked burials. Surveys in areas having potential for military sites need to be sensitive to the following: 1. A thorough visual observation of the ground surface needs to be conducted to identify surface features (huts, chimney falls, latrines, etc.), broad scatters and/or clusters of building materials, and evidence of relic hunting. This is especially needed for transect surveys where it is likely that only a portion of the site is contained in the project area; 2. Areas of steep slopes (>15%), sometimes excluded from survey, need to be examined as slopes are often favored locations for military encampments; 3. Landscape features are key components to military sites and can be recorded as archaeological resources; and 4. Metal detector surveys are recommended because the majority of diagnostic items deposited at military sites are metallic. When implemented, the metal detector survey shall consider relevant factors such as the experience of the metal detector operator(s), the type of metal detector(s), ground cover, intensity of survey coverage, extent of previous relic hunting, and environmental factors. A system of interpreting battlefield landscapes known as the KOCOA system (explained below) has been adopted by the NPS and endorsed by the American Battlefield Protection Program for the evaluation of historic battlefield environments. It encompasses key landscape features that may have affected or directed the military action in a given location and keeps the evaluator from focusing solely upon archaeological remains or built environment such as earthworks: K: Key terrain (terrain that must be taken or held to obtain victory); O: Observation and fields of fire (terrain that permits observation of enemy movements and avenues of approach); C: Cover/concealment (terrain that provides troops with cover or protection from enemy fire); O: Obstacles (features that stand in the way of seizing key terrain – these can be natural, such as heavy woods or deep swamp, or man-made such as fencelines, ditches or earthworks); and A: Avenues of approach (terrain by which the enemy may be approached – this can be anything from an established roadway to an open field). Underwater Sites Archaeological testing in underwater settings often involves unusual circumstances. Research designs for underwater Phase I surveys are to be discussed in advance with MDAH. In general, identification efforts in an underwater setting are to include: 1. Placement of exploratory units based on remote sensing results and knowledge of the sunken vessel or submerged cultural remains; 2. Use of mechanized equipment where extensive modern overburden present; 3. Careful examination of air-lifted and water-dredged soil samples. The soil samples must always be screened through mesh or net bagging; 4. Recordation of the excavation procedure to include drawings and photographs if visibility permits; and 5. Compliance with safety standards of nationally recognized diving organizations (PADI, Instructors NAUI, SSI, etc.). Metal Detection Research designs and proposed methodologies for metal detecting must be discussed in advance with MDAH staff, and any relevant Federal agencies. Avocationalists should be interviewed regarding their knowledge of the area. Use judgement when involving avocationalists. If looting has and continues to be a strong possibility, then involving avocationalists may not be appropriate. It is suggested that devices be recent models and professional grade, as technology is always improving. 1. Coverage: When required during Phase I, metal detector coverage should be systematic along 1.5 meter lanes on transects at a maximum 30 meter interval, though closer or even overlapping coverage may be necessary to meet specific research objectives; and removal of ground vegetation and/or leaf litter along detection lanes may be needed for metal detecting to be effective. 2. Reporting: Equipment, personnel, and time spent should be clearly stated in the methods section. Coverage, mapping, and artifact collection strategies should likewise be clearly stated. 3. Personnel Experience: Although recommended, no specific metal detecting training course is required. Preferred qualifications: a. Principal Investigators/Field Directors: have at least 100 hours hands-on field experience and/or equivalent training with remote sensing applications, when those applications are the primary focus of the archaeological investigation; and b. Other investigative personnel: the skills of all other investigative personnel must be appropriate to the requested task(s), the nature of the project, and to the goals and specifications delineated in the research design.