Chesapeake Bay impact site. Landsat 7 satellite photograph of Chesapeake Bay, USA, with elliptical rings to indicate the size and location of its impact crater. The Chesapeake impact crater is buried under 300-500 metres of sediment and water. It was formed when a 3-5 kilometre sized object hit the Earth 35 million years ago. The outer ring (85 kilometres in diameter) is the outer rim of the crater and the inner ring is the peak ring (38 kilometres in diameter).