Stratigramma

Stratigramma is a diagram used in geology and archaeology to depict the stratigraphic relationships among sedimentary units and other stratified deposits. The word combines stratum, meaning layer, with gramma, meaning a drawn figure. A stratigramma typically presents a stratigraphic column with units arranged from oldest at the bottom to youngest at the top, and it may include information on lithology, fossil content, and relative ages. In practice, stratigrammata may be simple vertical sketches or more elaborate panels that also show cross-sections, lateral correlations, and marker beds.

Construction and variations: A stratigramma requires choosing an orientation (vertical column or pair of sections), a time framework, and consistent coding for lithology and fossils. Units are shaded or colored to indicate rock type, age, or depositional environment. Correlation lines may connect equivalent beds across outcrops or boreholes, illustrating lateral continuity and changes in facies.

Uses: The diagram is used to visualize deposition history, facilitate correlation across spaces, guide field mapping and sampling, and assist resource assessment in hydrocarbon, groundwater, or mineral exploration. In archaeology, stratigrammata help interpret site formation processes by showing the sequence of occupational layers and their relationships.

Limitations: The accuracy of a stratigramma depends on reliable dating, complete exposure, and robust correlation; gaps, diachronous beds, and reworking can complicate interpretation.

See also: Stratigraphy, Stratigraphic diagram, Stratigraphic column, Lithostratigraphy, Biostratigraphy.