The FGDC Digital Cartographic Standard for Geologic Map Symbolization, released in 2006, provides guidance and assets for the preparation of geologic maps. It includes a large array of reference styles for geologic linework and map symbology.
This repository contains the entire FGDC pattern library extracted to SVG and PNG, for use on the modern web. This can be paired with collections of linework and geologic symbols for the construction of slick geologic maps and stratigraphic columns.
Additionally, this package includes a catalog of brushes for the iPad drawing app Procreate, which supports the sketching of geologic maps and stratigraphic columns. These can be found on the "Releases" page.
See the DOCUMENTATION for an index of symbols, usage and next steps.