A column is Macrostrat's record of the rock succession at a place. Columns are built from stacked units: bodies of rock or sediment bounded in both space and time. The column model is the oldest part of Macrostrat and the basis of most of its scientific results.
Columns
Each column has a location and, usually, a footprint: the area it represents, stored as a polygon. Columns are tiled across a region so that every point falls within one, which lets Macrostrat answer "what is beneath this location?" and sum rock quantities over areas.
Columns come in two types:
- Columns proper are composite records, typically compiled at basin or regional scale from published stratigraphic summaries (for example, the COSUNA charts for North America). Units are ordered in geologic time. Most of Macrostrat's columns are of this kind.
- Sections are records of one physical succession, such as a measured outcrop section or a drill core, where units are positioned by stratigraphic height.
Both use the same data structure. Superposition can be tracked against height or against time, so the system can hold anything from a regional composite with no single physical locality to a centimetre-scale core log.
Columns are grouped into column groups (for example, the columns of one basin) and into projects. A project is a dataset developed in its own right inside Macrostrat: the core North American compilation, ocean-drilling cores (the eODP project), or focused compilations of particular basins and time intervals. Projects let new datasets grow without disturbing the core dataset. A column's status records whether it is part of the public, active dataset or still in process.
Units
A unit describes a body of rock with consistent character. It carries:
- a stratigraphic name, where one applies, linked to the Geologic lexicon;
- lithologies (dominant and subordinate rock types) and lithology attributes such as sedimentary structures, bedforms or grain sizes;
- depositional environments and economic attributes;
- thickness, as a single value or a minimum and maximum;
- ages, from the column's Age model;
- references to the publications the description comes from.
Units can be linked to records held elsewhere: fossil collections in the Paleobiology Database, geochemical and other measurements, and the units of Geologic maps (see Linking data).
Sections and packages
Within a column, units can be grouped into sections: unconformity-bounded packages within which time is represented continuously. (These are distinct from the section column type above.) Packages mirror how stratigraphers already reason about the rock record, and they bound where the age model may interpolate.
Getting columns into Macrostrat
New column data are prepared as spreadsheets in Macrostrat's column ingestion format (see Format documentation), which describes columns, units, facies, metadata and references in separate sheets. The format is loaded by Macrostrat's command-line tools. A web-based column editor is in development; contributors interested in adding columns should get in touch (see Contributing).
Getting columns out
Columns, units and their footprints are available through the public API, in JSON, CSV and GIS-ready formats. See Accessing column data and Data services.
