In time, much of the gas found its way into porous rocks, sometimes forming vast reservoirs, or gas fields, that were sealed beneath a layer of impermeable rock.
Baada ya muda, gesi nyingi iliingia kwenye miamba yenye vinyweleo, nyakati nyingine ikafanyiza hifadhi kubwa, au visima vya gesi, ambavyo vilikuwa vimezibwa chini ya safu ya miamba isiyoweza kupenyeza.