A shallow offshore area of the ancient Gulf of Mexico eventually became the land on which downtown Wetumpka was built and through which today's Coosa River flows. During the late Cretaceous, about 85 million years ago, a very large stony meteor about 1,200 feet in diameter, roughly the size of a large college football stadium, struck this shallow sea and blasted about 2,000 feet deep into local bedrock, causing Alabama's greatest natural disaster. At the time, North America was divided by an interior seaway, central Alabama lay along the shoreline, marine reptiles, fish, and turtles inhabited the sea, and dinosaurs lived on nearby land. Traveling approximately 43,000 miles per hour, the meteor heated in the atmosphere, then impacted water about 100 feet deep and produced a 2.6 billion-ton TNT explosion. In the first minutes, impact forces compressed and shocked rocks, excavated and ejected debris, and then formed the crater as the center rebounded several hundred feet. The explosion threw rock debris into the atmosphere, with some reaching low Earth orbit, triggered a 9.0 earthquake, caused flash fires along the nearby shore, and sent winds stronger than a violent hurricane more than 15 miles outward. Within the first three minutes, ejected rocks fell within a thirteen-mile radius, causing injury and destruction of life. The crater developed sides up to 1,000 feet high except where the south side collapsed, and a tsunami moved outward and then returned, bringing sea-floor sediment from the south. Within the crater, rock layers in the area known as The Cliffs slid across the crater floor and collided with the rim, leaving disturbed and folded layers still visible there today. As life returned, an ecosystem developed on the crater island, which remained in the Gulf of Mexico for millions of years until sea level receded. The crater was then eroded, buried in sediment, and later became dry land; after the Coosa River developed, it first flowed over the buried crater and later changed course to bend around the crater rim. The Wetumpka Impact Crater, 4.7 miles in diameter, is the only confirmed impact crater in Alabama and one of only about 200 recognized craters, with its age determined from fossils in the youngest disturbed deposits and atomic age-dating of impact-affected crystals. The arc of hills east of the Coosa River and downtown Wetumpka are the eroded remains of the crater's rim, and the rocks in the Coosa River are part of that rim.