Faulted, slickenlined petroliferous limestone, Appalachian Mountains, West Virginia

&lt;p&gt;This wedge-shaped block of limestone is enclosed by fault surfaces marked by slickenlines. &amp;nbsp;The slickenlines are mainly crystal-fiber lineations of calcite. &amp;nbsp;The origin of the calcite vein material was undoubtedly pressure solution. &amp;nbsp;The limestone itself is very dark gray in appearance. &amp;nbsp;Hardened oil locally coats the fault surfaces.&lt;/p&gt;

Whereabouts

I collected this near Seneca Rocks, West Virginia, back in ~1966. My wife and I were touring part of "West by god Virginia" (proud name applied by proud people) with my parents, and I just ‘happened’ to see a fine fault exposure in one of the road cuts, and managed to bring this home with me. I like the fact that in this one small rock it is possible to see the intersecting of faults, and with a coordination of movement that is clear in the slickenline orientations. Moreover, this rock is a great example of zones of fault intersections becoming places where fluids, in this case hydrocarbons, migrate because of the porosity and permeability of such zones.

Age & Formation

Paleozoic limestone. Formation uncertain.