LithoMap, a field map for what lies beneath

Field notes

LithoMap layers geologic units with fossil records from the Paleobiology Database and mapped USGS records for collectible rocks, minerals, gems, and precious metals. Users can adjust geology visibility, inspect formation details, and add public-land context before saving an area for offline use; the page says interrupted downloads can resume. The listed Offline Basic tier allows three active offline areas, while paid memberships are described as being prepared for launch.