Earth Impact Characteristics

• 150 known craters/fields + ~4 new/year; majority <200My
• All entirely on land, except Montagnais, Chesapeake, Chicxulub
• Bias towards large (longer-preserved); up to 300 km diameter
• Bias towards young; majority <200My, in contrast with (lunar) frequency

• Simple: usually <4 km dia; impact, maximum depth and dia, collapse leaves breccia lens and ejecta blanket
• Complex >4 km dia; central uplift, slumped rims, multiple rings

• Shocked Minerals
• Tektites, Microtektites and Impact Glasses
• Ir Anomaly
• Impact Breccias and Tsunami Deposits

Courtesy NASA, Johnson:

• Crater simulation
• Oblique crater simulation