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→Example: smear gouge
[[file:evaluating-top-and-fault-seal_fig10-20.jpg|300px|thumb|{{figure number|1}}Smear gouge along a normal fault found in a sequence of Permian-Carboniferous sand and shales near Lynemouth, U.K..]]
[[file:evaluating-top-and-fault-seal_fig10-20.jpg|300px|thumb|{{figure number|1}}Smear gouge along a normal fault found in a sequence of Permian-Carboniferous sand and shales near Lynemouth, U.K..]]
[[:file:evaluating-top-and-fault-seal_fig10-20.jpg|Figure 1]] is an example of smear gouge along a normal fault found in a sequence of Permian-Carboniferous sand and shales near Lynemouth, U.K. Ductile, light gray shales have been incorporated in the fault zone as a continuous layer sourced from a bed in the footwall (upper left). Similarly, a bed of coal (black) in the footwall and sandstone in the hanging wall have been incorporated as discontinuous fragments in the fault zone. The coal, however, is intensely fractured, reflecting brittle rather than ductile deformation.
[[:file:evaluating-top-and-fault-seal_fig10-20.jpg|Figure 1]] is an example of smear gouge along a normal fault found in a sequence of Permian-Carboniferous sand and shales near Lynemouth, U.K. Ductile, light gray shales have been incorporated in the fault zone as a continuous layer sourced from a bed in the footwall (upper left). Similarly, a bed of coal (black) in the footwall and sandstone in the hanging wall have been incorporated as discontinuous fragments in the fault zone. The coal, however, is intensely fractured, reflecting brittle rather than [[Ductility|ductile]] deformation.
Shale-rich gouge zones can create impermeable barriers. The following, a normal fault in Jurassic and Triassic sediments near Lilstock, U.K., shows a gouge zone approximately [[length::5 m]] thick. The gouge consists predominantly of ductile shales and marls as well as small amounts of brittle limestones. Faults with similar shale-rich gouge in producing fields create seals.
Shale-rich gouge zones can create impermeable barriers. The following, a normal fault in Jurassic and Triassic sediments near Lilstock, U.K., shows a gouge zone approximately [[length::5 m]] thick. The gouge consists predominantly of ductile shales and marls as well as small amounts of brittle limestones. Faults with similar shale-rich gouge in producing fields create seals.