= Solution
The coarse angular fragments in the light-coloured band identify a \b[<fault breccia>], probably cemented and accompanied by finer comminuted material. Repeated brittle fracture, clast rotation and crushing during <fault slip> produce the fragments; fluid flow can later fill pores and fractures with mineral cement. If the finer material is cohesive it can be termed <cataclasite>; a loose, very fine seam is <fault gouge>. The photograph alone does not establish all those <cohesion> and grain-size distinctions.
Slip is commonly concentrated on a narrow principal slip surface or fine-grained seam at a margin or inside a broader damaged band. Thus the coarsest, widest breccia is not automatically the material that accommodated the largest shear displacement. In this image the sharp, finer-looking boundaries of the coarse band are the best candidates for localized slip. Identifying the uniquely most displaced seam would require displaced markers, thin sections or additional exposure; the coarse band itself records substantial distributed damage.
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