The Sudbury impact structure in Ontario, Canada is a deformed and eroded impact crater. Dating using zircon minerals places the impact at 1.849 billion years ago. Shatter cones were created by the shock wave propagating through the target rock. This type of impactite is the only diagnostic macroscale evidence for the shockwave of impact processes. While this specimen measures some 20-25 cm in size, some outcrops contain shatter cones that are much larger. Since the impact, various geologic processes, such as mountain building and erosion, have reduced the crater that could have been as large as 130 km, into a somewhat oblong impact scar of 62x30 km. Despite the passing of geologic time, the tell-tale structure of these shatter cones have been preserved in the rock.