Between 100 and 200 millions of years ago, a meteor nearly 1,000 feet in diameter, weighing more than 100 million tons and traveling more than 10 miles per second, struck the earth at this location with shattering force. Scientists believe it penetrated about 2000 feet before exploding, sending shock waves in all directions and raising a fiery mushroom cloud of fine rock dust and debris high into the air. The impact created a crater about four miles in diameter and one-half mile deep, and scientists believed the earth's surface appeared to be damaged forever. Over millions of years, erosion and vegetation softened the scar left by the impact, the rim of shattered rock disappeared, and the level of adjoining land was lowered hundreds of feet by erosion. Since its discovery, geologists have studied this phenomenon, which was found about 1860 when railroad construction revealed rock formations suggesting that a violent event had occurred.