First geological map of the United States (Maclure)
Primer mapa geológico de Estados Unidos (Maclure)
- Date
- 1809 · confidence high
- Place
- Philadelphia, Pennsylvania, United States
- Credited to
- William Maclure
- Field
- Cosmos & Earth
What was discovered
After travelling most of the country on horseback and on foot, William Maclure published in 1809 a geological map of the United States grouping rocks by type and relative age, using Werner's scheme (primitive, transitional, secondary and alluvial).
He reissued the map, enlarged, in 1817. His Wernerian classification was later replaced by fossil-based stratigraphy.
What it led to
- a model for state geological maps and state geological surveys
- North American geology organised by formations