A stratigraphic trap or structural feature where a specific bed, seam, or orebody gradually thins out and completely disappears between enclosing rock layers. In resource extraction, it marks the physical end of a continuous deposit. Oil and gas geologists actively hunt for pinch-outs because the impermeable surrounding rock often traps migrating hydrocarbons at the tapering edge.
Heard on the job
The coal seam hits a pinch-out against the sandstone roof about fifty meters past the last crosscut.
Insider tip
A pinch-out is usually a depositional feature where the material was never laid down, whereas a fault cuts off an existing layer.