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A thick wedge of Precambrian crystalline rocks of the Wind River Mountains was thrust far across sediments of the Green River basin during the Laramide orogeny. Dip of the thrust zone decreases with depth to form a broadly curved, convex-downward surface. Seismic data also show strong local curvatures that produce a scalloped pattern in the leading edge of the thrust wedge and divide the wedge into lobate segments that are about 8 mi (13 km) wide along strike. The explanation for this scalloped pattern of folding may be lengthening of the unconfined wedge margin by extension during thrusting. Curvature of the thrust surface confirms that deformation of Precambrian rocks occurred by a foldlike mechanism. Local curvatures can also explain low apparent-dip angles of some oth r thrust faults in the Wyoming foreland.
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