Cross Section A-B

This cross section shows the wedge of  porous Yesnaby Sandstone caped and under-sealed by impervious sediments. The Yesnaby Sandstone forms a classic "Combination Trap" for oil accumulation - both stratigraphic and structural in nature.

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The aeolian (desert) and fluvial (river) deposited sands of the Yesnaby Sandstone commonly are blackened by solid bitumen indicating the former presence of hydrocarbon liquids (crude oil).