Paleontology and geology

There are no surface rocks of Jurassic age in Alabama. Analysis of drill cores indicates that fluctuating sea levels caused intermittent flooding of the rift valleys formed earlier in the Triassic. At times, rates of evaporation exceeded rates of water inflow to these areas and the sea dried up, leaving behind beds of pure salt. Eventually the sea persisted, creating the young Gulf of Mexico. As the Gulf widened and deepened through the Jurassic, rich deposits of hydrocarbons—formed primarily from decaying single-celled organisms—accumulated in the sediments. These hydrocarbons became the valuable petroleum and natural gas deposits now found across the modern Gulf States and Mexico.