Figure 33. Block diagrams showing different geometries of thrust faults that result in the formation of tectonic windows. Teeth are on upper plate of thrust fault; small arrows show fault movement sense. A, Tectonic window formed by erosion of a simple duplex. B, Tectonic window formed by erosion of a slightly warped or undulating duplex. C, Skewed tectonic window exposed by erosion near the intersection of a lateral ramp and a frontal ramp. D, Blunt-ended tectonic window formed from a pair of lateral ramps.