Geospatial Analysis
Using location to answer questions across data layers: what overlaps, what is near, what lies where, and what follows the terrain.
Detailed Definition
Geospatial analysis is asking questions of data by where things are. USGS gives an example: by knowing where farms use a particular fertilizer, "GIS analysis of farm locations, stream locations, elevations, and rainfall will show which streams are likely to carry that fertilizer downstream." No single layer holds the answer. It comes from lining the layers up by location. See GIS.
Common methods
- Joins by location: attaching the attributes of one layer to another, such as the township and section each mining claim falls in. See Spatial Join.
- Proximity: drawing zones a set distance around features and finding what falls inside. See Buffer Analysis.
- Surface analysis: deriving new values from rasters. Esri notes that elevation "can be used to derive slope, aspect, and watershed properties." See DEM.
- Classification: grouping raster values into classes, such as "classifying a satellite image into land-cover categories" (Esri).
- Comparison over time: the same area, or the same records, at two dates.
Results inherit their inputs
An analysis is no better than its data. BLM states on its PLSS and mining claim layers: "The data are not better than the original sources from which they were derived, and both scale and accuracy may vary across the data set." Method choices matter as well. Distance depends on projection, which is why Esri offers geodesic options for data that "covers a large geographic extent." Spatial joins depend on the relationship chosen, and when two features are equally close, Esri's Closest option picks one at random. See Projection.
Survey accuracy is a different standard
BLM's Manual of Surveying Instructions (2009) requires a surveyor to report "the mathematical uncertainty of the geographic coordinates computed" (section 2-32), and it notes that the spatial depiction of the PLSS in a digital system "is a byproduct of the abstraction of data from official survey records" (section 2-37). An overlay of mapped layers finds candidates. It does not fix boundaries.
Why it matters in mining claim research
Geospatial analysis is how conflicts, gaps, and patterns get found: mining claims overlapping each other, mining claims on withdrawn land, and open ground between blocks of mining claims. Each finding is a lead to verify, not a conclusion. Because BLM most commonly maps mining claims to quarter sections, an overlap in the GIS shows that two cases share a quarter section, not that their staked boundaries cross. The location notices, plats, and field notes decide that.
Related Terms
Geospatial AI
Artificial intelligence applied to maps, imagery, and location data. USGS uses machine learning to georeference historical maps and model mineral prospectivity.
Remote Sensing
Gathering information about the Earth from a distance by measuring reflected and emitted energy, usually from satellites or aircraft.
GIS
A geographic information system: software and data that store, analyze, and display information tied to locations on the earth.
Spatial Data
Data that identifies where something is on the earth and what it is like, stored as vector features, raster grids, or coordinates in records.
Geocoding
Turning a written location, such as a street address or a legal land description, into map coordinates or a polygon.
Spatial Join
A GIS operation that copies attributes from one layer to another based on where features sit relative to each other, not on a shared field.
Buffer Analysis
A GIS operation that draws polygons a set distance around points, lines, or polygons, used to find what lies within that distance.