Measured occurrence
A published analytical observation of H₂. Method, units, date and location may still have gaps.
H2A / METHODS & UNCERTAINTY
Make uncertainty
part of the evidence.
How H2A distinguishes evidence types, preserves provenance and communicates what is missing.
Evidence categories are different kinds of information.
They are not a universal ranking or a numerical quality score. A well-documented model and a measured observation answer different questions.
Documented reservoir / use
A source describes a hydrogen-bearing reservoir or actual use. Economic reserves are not inferred.
Indirect geological indicator
A geological, geophysical or morphological observation that may guide research; not a hydrogen measurement.
Prospectivity model
A modeled combination of assumptions and geological information. Source classifications are retained.
Research reference / hypothesis
A source-linked research context. Representative points are not survey station coordinates or field boundaries.
REGIONAL COMPARISON
Compare the evidence, not an invented score.
Select two Algerian research domains to compare their published context and metadata completeness.
MISSING DATA
An explicit limit is useful information.
Algerian H₂ measurements, detailed geological polygons, structural layers and geophysical grids are not integrated in this release. A lack of displayed observations must not be interpreted as no hydrogen. Country-level global cases are not precise locations.
The USGS display is a cartographic derivative of official vector layers, generalized by 0.025° at retrieval and rasterized for fast viewing. Use the source geospatial data for quantitative analysis.
PROVENANCE & ATTRIBUTION
Respect the source. Preserve the meaning.
U.S. Geological Survey
Map services and data are available from the Prospectivity Mapping for Geologic Hydrogen dataset provided by the U.S. Geological Survey via https://doi.org/10.5066/P13WCG5U.
CC0 / public domain. No endorsement by USGS is implied. The original class colors and breaks are retained.
Natural Earth / OpenStreetMap
Local country boundaries: Natural Earth 1:110m, public domain. Optional street basemap: © OpenStreetMap contributors, ODbL. Generalized boundaries are for geographic context, not legal delimitation.
Scientific literature
Bibliographic metadata and original concise summaries are provided with direct source links. No subscription article, commercial occurrence database or private project document is republished.