The horizontal surface area covered by an archaeological feature as measured in plan view and expressed in square units; it is the orthogonal projection of the feature onto a defined horizontal datum and must be reported with the datum and method of projection.

Principle

Feature area quantifies the planimetric extent of a feature and, when paired with thickness or volume, determines the feature's size; measured values depend on the chosen projection and the scale of measurement.

Demonstration

Illustrative scenario — Situation: a rectangular pit is recorded with internal plan dimensions 2.0 m × 1.5 m. Recognition: boundaries are clear in plan. Action: area = 2.0 m × 1.5 m = 3.0 m²; record datum and projection. Consequence: area is used to compute artifact density per square metre and to compare spatial footprints of features.

Misapplication

Measuring exposed sloping surfaces instead of the plan projection, or reporting area without specifying the projection/datum, which produces non‑comparable results.

Consequence

Misreported feature area leads to incorrect areal densities, flawed spatial analyses, and poor comparability between contexts or sites.

Reversal

For vertical or highly irregular surfaces (e.g., walls, steep earthworks), plan area underestimates the true surface extent; surface area (three‑dimensional) may be the appropriate metric in those cases.

Boundary

Clearly within: a pit, hearth or structure with a definable plan outline. Boundary case: a diffuse scatter of postholes that may or may not form a single feature in plan. Clearly outside: linear transects of erosion measured along slope without plan projection.

Semantic Tension

Simplicity and comparability of planimetric area ↔ the geomorphic or architectural reality of three‑dimensional surface area.

Synthesis

Feature area is a planimetric descriptor whose usefulness depends on explicit statement of datum, projection and the intended conceptual projection; when surface complexity matters, pair plan area with measures of surface area or volumetric extent.