Legend: colours and patterns
How each lithology code is drawn.

- FGDC patterns: The patterns are the US Federal Geographic Data Committee’s geologic map standard (public domain): 601-686 sedimentary, 701-733 metamorphic, igneous and vein rocks.
- First guesses: Each code’s pattern and colour are guessed from its description (granite, tuff, limestone …). A code with no match gets a plain colour.
- Your legend: Download the legend as CSV, change any COLOUR (#RRGGBB) or FGDC_PATTERN number, and load it back. Your choices replace the guesses.