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While the days of the "gusher" is a thing of the past (which is a good thing - gushers are extremely dangerous and damaging to the environment), plenty of oil and natural gas production is still occurring in onshore areas of Texas, Louisiana, Oklahoma, Kansas, and Arkansas.
Just onshore, in south eastern Texas and southern Louisiana, the flowage of salt domes has been the predominant mechanism for creating traps for oil. Salt of Jurassic age occurs here. When it is put under immense pressure by overlying rocks, this salt, which is less dense than the rocks surrounding it, will begin to flow upward. As it does so, it displaces, folds, and faults the rocks around it. In this way, traps can be created.
The Louann Salt is more than 200 million years old, and is located at great depths along the Gulf of Mexico's shoreline. In some places, however, this salt has moved due to the enormous pressure being put on it from the rocks above. The map below shows us exactly where the Louann Salt is located below the surface (south of the blue line), and where structures (dark green "blobs" on the map) have been created by its underground movement.
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