Folding

Bending of geological layers during deformation. A buried fault can produce folding without a throughgoing primary rupture at the surface.

Relative movement parallel to bedding during folding, allowing layers at different radii of curvature to accommodate different arc lengths. For two layer surfaces separated by thickness $h$ through bend angle $\theta$, their arc-length difference is approximately $h\theta$. Bedding-parallel slip can accommodate that mismatch without requiring each layer to stretch by the same amount. Shallow flexural slip can produce surface breaks above a blind reverse fault.

A step-like bend linking relatively less tilted beds on either side. Distributed deformation above a blind fault can produce a monocline without a discrete surface break.

A topographic step or steepened belt produced by localized folding. It can form above a blind reverse fault without being the trace of the principal fault plane.

A fold formed as displacement is transferred ahead of a propagating fault tip into surrounding rock. It is one mechanism for surface deformation above a blind reverse fault.

A fold with older layers in its core where the age relationships are preserved. Active blind reverse faults can produce asymmetric anticlines and warping of young landforms.