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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 [[Brittleness|brittle]] rather than [[Ductility|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 [[Brittleness|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.