TS 4228

TS 4228 is a symbol-based standard for showing metamorphic rocks on geological maps and geological cross-sections. In mapping and section drawing, such symbols help communicate rock type and geological character in a compact, readable, and consistent way, so the same field information can be interpreted more uniformly across different drawings.

Metamorphic rocks form when pre-existing rocks are transformed by pressure, temperature, and fluid activity, producing changes in mineralogy and texture. In geological documentation, separating these rocks into dedicated symbols matters because different metamorphic rocks, such as gneiss, schist, and marble, carry different implications for geological history and for the interpretation of terrain and engineering conditions. In general technical practice, symbol systems replace lengthy textual descriptions with standardized visual codes, improving clarity and map legibility.

What the symbol set is for in geological drawing

The subject covered by this standard is the graphical representation of metamorphic rocks on geological maps and cross-sections. Its role is to provide a common visual language for translating rock names and geological interpretation into drawing conventions. This makes it easier for different organisations, projects, and drafting teams to depict the same rock types in a similar way, which supports comparability and technical communication.

• Helps distinguish rock types visually on geological maps.
• Supports consistent presentation of subsurface interpretation in cross-sections.
• Establishes a standard drawing logic for metamorphic rock representation.
• Improves map reading and communication between field and drafting work.

TS 4228 is the metamorphic-rock part of a geological symbol system and is sourced from ISO 710-4:1982. This listing is withdrawn, but it remains useful as a technical reference for understanding why geological drawing conventions are divided into subject-specific symbol groups.