The Cretaceous period occurred about 65-145 million years ago, and is the most recent part of the Mesozoic era.   The Upper/Late Cretaceous period consists of the Tuscaloosa group and the Selma group.  Most fossils are found in the Eutaw Formation, Mooreville Chalk/ Arcola Limestone Member, Demopolis Chalk, the Ripley Formation, and Prairie Bluff Chalk.  In appearance, most of the "dirt" in these formations is white to light gray chalk, fairly soft and easy to remove unless it has been compressed.

In Alabama, the Cretaceous makes a swath from upper-middle west Alabama, across to Montgomery, then on to the Auburn area.  About 80 million years ago mosasaurs were swimming in the oceans, and eating pretty much whatever they desired, including ammonites, sharks, and giant sea turtles.  Today, Alabama is known for extensive fossil remains found in the chalk beds of southern Alabama, and washed out of the chalk into numerous creekbeds.