Structural measurement types

Planar structures are recorded as a strike and a dip; linear ones as a trend and a plunge. The Atlas separates 10 types across 814,797 measurements, keeping the publisher's own term on every row.

Planar structures — strike and dip

Bedding — 293,477

The primary layering of a sedimentary rock, and the reference surface almost all structural analysis is built on.

Foliation — 194,290

A planar fabric produced by deformation or metamorphism — schistosity, gneissic banding, the alignment of platy minerals.

Other — 176,772

Rows whose published type could not be resolved to one of the categories above. The original term is preserved on every record.

Joint — 51,753

A fracture with no measurable displacement across it. Joints come in sets, and the sets record the stress field.

Vein / dike — 20,175

A tabular body filling a fracture: mineral precipitate (vein) or intruded magma (dike). Its orientation maps the opening direction.

Cleavage — 19,298

A closely spaced planar fabric along which a rock splits — commonly axial-planar to folds, which makes it a proxy for fold geometry.

Fault plane — 9,942

The surface across which rock has measurably moved. Attitude alone does not give the slip — that needs a lineation on the surface.

Linear structures — trend and plunge

Lineation (mineral, stretching) — 39,214

A linear fabric element — stretched grains, aligned minerals, an intersection. Recorded as trend and plunge, and often parallel to transport.

Fold hinge / axis — 8,253

The line of maximum curvature in a folded surface. Fold axes define the structural grain of a region.

Slickenline — 1,623

Striations on a fault surface recording the direction of slip. With the fault plane, this is a fault-slip datum.