Macrostrat describes the rocks of the Earth's crust in space and time. It brings together three kinds of information that geologists normally keep apart, and links them so that a question asked of one can be answered with the others:
- Stratigraphic columns record successions of rock units at a place: what lies on top of what, how thick it is, what it is made of, and when it formed. Every column carries an Age model that ties its units to the geologic timescale.
- Geologic maps record where rock units crop out at the surface. Maps from many organizations, at scales from quadrangles to the globe, are brought into one harmonized, multiscale map.
- The Geologic lexicon is the shared vocabulary that makes the first two comparable: stratigraphic names, lithologies, depositional environments, economic resources, and the intervals of the geologic timescale.
Around this core sit records from other systems: fossil collections, geochemical samples, ocean-drilling cores and descriptions mined from the scientific literature. They attach to Macrostrat's units through the same lexicon, by location and by age (see Linking data).
How the pieces fit
| Component | What it holds | Where to read more |
|---|---|---|
| Columns and units | Successions of rock and sediment, with lithologies, environments, thicknesses and ages | Stratigraphic columns, Age model |
| Lexicon | Controlled vocabularies and the timescale | Geologic lexicon |
| Map sources | Individual geologic maps: polygons, lines, points and their legends | Geologic maps, Map ingestion |
| Compilations | Multiscale maps assembled from many sources, served as one map | Map compilations |
| Links | Matches between map legends, column units, names and outside records | Linking data |
| Literature | Entities and relations extracted from geologic papers | Knowledge graph |
All of it lives in a single PostgreSQL/PostGIS database and is served to the world through public APIs and map tiles (Data services). Macrostrat's own website, the Rockd mobile app and many third-party applications are built on those services. How the software is put together is described in System architecture.
Design principles
A few ideas recur throughout the system:
- Time is first-class. Units are positioned in geologic time, not just in space. Ages come from an explicit model that can be refined as constraints improve, and every derived age (for a map unit, a fossil, a sample) traces back to it.
- Multiscale by construction. The same data structures hold a global compilation and a single measured section, a continental map and a quadrangle. Detail is added where it exists without breaking the coarse picture elsewhere.
- Harmonize, but keep the source. Maps and columns are translated into Macrostrat's shared vocabulary so they can be compared, but each record keeps its original description and its reference.
- Open by default. Data are available through public APIs under a CC-BY license, and the software is open source.
If a term is unfamiliar, the Glossary defines the vocabulary used across these pages.
