Excavation (archaeology) Study Guide

📖 Core Concepts Excavation – exposure, processing, and recording of archaeological remains; the “dig” where data are recovered. Artifacts, Features, Ecofacts – portable objects (e.g., pottery), non‑portable modifications (e.g., hearths, cuts), and organic remains (e.g., pollen, charcoal). Context – the exact three‑dimensional location of an artifact/feature and its relationship to surrounding material; the basis for dating and interpretation. Stratigraphy & Law of Superposition – deposits accumulate layer‑by‑layer; lower layers are older than those above them. Harris Matrix – a two‑dimensional diagram that orders all contexts chronologically using arrows to show “earlier → later”. Phase – a near‑contemporaneous snapshot of the site; a collection of contexts that belong to the same occupational episode. Intrusive Object – a later‑dated item that has entered an older layer, potentially confusing the sequence. Single‑Context Recording – each context gets a unique number and is documented on sheets, plans, and sections. Strip‑Map‑Sample (UK) – rapid assessment method for development‑led projects: strip overburden, map visible features, sample key areas. --- 📌 Must Remember Law of Superposition: Lower = older, Higher = newer. Context = Location + Relationship – always record both. Harris Matrix shows temporal (not spatial) relationships. Phase vs. Context: Phase groups many contexts; a context is a single depositional event. Intrusive objects indicate post‑depositional disturbance; never assume they are primary. Single‑Context Sheet must include: context number, description, dimensions, plan, section, finds list, and dating notes. Rescue vs. Development‑Led vs. Research Excavation: Rescue – emergency salvage, tight time frame. Development‑Led – funded by developer, focused on construction‑impacted area. Research – full‑scale, hypothesis‑driven, ample time. Strip‑Map‑Sample is used only when full excavation is impractical (e.g., large urban development). --- 🔄 Key Processes Stratigraphic Excavation Procedure Remove topsoil → identify discrete edges of each context → assign a unique number → record on context sheet/plan/section → excavate contexts in reverse order of creation (latest → earliest). Creating a Harris Matrix List all contexts → draw arrows from earlier to later (cut → fill, pit → back‑fill) → group into phases, sub‑groups, etc. Single‑Context Recording Workflow Measure height (ASL) → photograph → fill context sheet → bag & label finds (site‑code + context #) → enter data into digital database. Flotation & Sieving (Finds Processing) Flotation: Place soil in water; floating material (seeds, charcoal) collected on mesh. Sieving: Pass soil through graded screens; retain artifacts > mesh size. Spot Dating Specialist examines fresh context → provides immediate relative/absolute date → adjust excavation strategy if anomaly appears. --- 🔍 Key Comparisons Artifact vs. Feature vs. Ecofact Artifact: portable, moved (e.g., pottery). Feature: non‑portable, part of the site fabric (e.g., ditch). Ecofact: organic, not human‑made (e.g., animal bone). Rescue Archaeology vs. Development‑Led Excavation Rescue: emergency, often limited to salvage; time‑critical. Development‑Led: planned ahead of construction; funded by developer, may allow limited research. Mechanical vs. Manual Excavation Mechanical: fast removal of overburden; risk of damage, used in salvage. Manual (hand): precise, preserves fine details; standard for research contexts. Strip‑Map‑Sample vs. Full‑Scale Excavation Strip‑Map‑Sample: quick, selective, limited to threatened zones. Full‑Scale: systematic, layer‑by‑layer, aims for complete reconstruction. --- ⚠️ Common Misunderstandings “Higher = more important.” Importance is not tied to depth; later layers can be less significant than earlier ones. “All objects in a layer are the same age.” Intrusive objects can contaminate a context. Always check for anomalies. “Mechanical excavation replaces hand excavation.” Mechanical removal is only for overburden; fine‑grained recording still requires hand work. “A phase equals a single year.” Phases can span decades or centuries; they represent a cultural horizon, not a calendar year. --- 🧠 Mental Models / Intuition “Layer cake” model: Visualize the site as a stacked cake; each slice (context) tells a story, and the frosting (fills) records the action of cutting the cake (dig). “Arrow of time” in Harris Matrix: Think of arrows as a family tree of deposits—parents (earlier cuts) give rise to children (fills). “Context as a GPS coordinate”: Treat each find as having a precise latitude, longitude, and elevation; losing any coordinate erases its meaning. --- 🚩 Exceptions & Edge Cases Post‑depositional disturbance: Bioturbation, root growth, or later construction can mix contexts; always look for soil color changes, compactness, and intrusive artifacts. Waterlogged sites: Flotation may be unnecessary; water already separates organics. Urban sites with deep modern fill: Modern fill can be several meters thick, masking older sequences; identify the “cut‑fill” interface before proceeding. --- 📍 When to Use Which Use Harris Matrix when you have ≥ 5 contexts with complex cuts/fills; otherwise a simple vertical profile may suffice. Choose Strip‑Map‑Sample for development‑led projects with tight schedule and budget constraints. Apply mechanical excavation only for overburden removal; switch to hand tools for any context containing artifacts/features. Employ flotation when you expect organic micro‑remains (seeds, charcoal); otherwise stick to sieving for macro‑artifacts. --- 👀 Patterns to Recognize Cut‑and‑Backfill Pair: Always appears as two consecutive contexts (cut → fill). Intrusive Object Pattern: A later‑dated artifact surrounded by older material → flag for possible disturbance. Phase Cluster: Multiple contexts sharing the same pottery styles, construction techniques, and radiocarbon dates → likely same phase. Spot‑Dating Red Flag: Unexpected ceramic style or dating within a context → triggers re‑evaluation of the Harris Matrix. --- 🗂️ Exam Traps Trap: Assuming “higher = later” without checking for intrusive objects → leads to reversed chronology. Trap: Selecting mechanical excavation for a feature‑rich layer → may destroy delicate evidence, causing loss of marks or small artifacts. Trap: Confusing feature with artifact (e.g., calling a hearth a “pottery shard”). Trap: Interpreting a single context as a phase; phases are groupings of contexts, not individual layers. Trap: Choosing full‑scale excavation for a development‑led site with limited time/funding – the answer choice will usually point to Strip‑Map‑Sample instead. ---