Interparticle friction within the deforming mass is 0.50; interparticle friction between internal and basal particles is 0.10, defining a weak horizontal decollement. The left boundary moves at a constant velocity, compressing the volume, causing uplift and folding of the colored layers, and discrete thrust faults. The weak decollement results in a shallow taper, and a very wide wedge.

Interpretation: Particle configurations show cumulative displacements of particles, and wedge deformation. Displacement vectors show what part of the system is moving. Displacement gradients denote discontinuities, i.e., instantaneous wedge structure; fore thrusts and back thrusts can be observed, as can the advancing deformation front and protothrust zone. Average particle differential stresses (darker colors) increase as the wedge grows, and principal stress orientations rotate to become subhorizontal with deformation.

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