Overview
ISO 710-2:1974 - Graphical symbols for use on detailed maps, plans and geological cross-sections - Part 2: Representation of sedimentary rocks provides a unified, extendable set of graphical symbols and ornaments for depicting sedimentary rocks on detailed maps, plans and geological cross-sections. The standard organizes symbols into two complementary groups (principal types and varia) and reproduces them in tables to support consistent cartographic and geological representation.
Key topics and technical requirements
- Two-group classification:
- Principal types (Table 1) - diagrammatic ornaments for common sedimentary rock classes (clastic, chemical and organic sediments).
- Varia (Table 2) - supplementary rock types, mineral inclusions and special features not suited to principal-type diagrams.
- Elementary symbols and composition: basic marks (dots, lines, particles) represent grain size and texture (detritus, sand, silt, clay) and are combined to form ornaments for more complex rocks.
- Representation rules:
- Irregular arrangement indicates loose (unconsolidated) material; staggered/systematic arrangement denotes consolidated rocks.
- Use of adjectives or petrographic qualifiers (e.g., argillaceous, calcareous) to refine rock identity.
- Grain-size variations rendered by adjusting symbol size/density (examples: coarse/medium/fine sand).
- Mineable deposits may be shown as black or densely cross-hatched areas; where this obscures detail, the underlying ornament is preferred and annotated in a legend.
- Special symbols: conventions for dolomite, gypsum, anhydrite, sodium/potassium salts, peat, ferruginous/siliceous character, caverns, concretions, mineral inclusions (feldspar, mica, glauconite), volcanogenic admixtures, fossils, and others.
- Extensibility: tables are derived from a logical system and can be completed or adapted to specific mapping needs. Box referencing uses column/line notation (for example, 3/12).
Applications and who uses it
ISO 710-2 is intended for professionals who produce or interpret geological maps, plans and cross-sections, including:
- Geological survey organizations and cartographers
- Mining and exploration geologists
- Environmental and engineering geologists
- Academic researchers and students in stratigraphy and sedimentology
Using standardized graphical symbols for sedimentary rocks improves clarity, interoperability and legibility across maps and technical reports.
Related standards
- ISO 710-1: General rules of representation (Part I)
- ISO 710-3: Representation of magmatic rocks (Part III)
- ISO 710-4 / 710-5: Forthcoming parts for metamorphic rocks and minerals (as noted in the standard)
Keywords: ISO 710-2:1974, graphical symbols, sedimentary rocks, geological mapping, cross-sections, cartographic symbols, geological symbols.