The document discusses criteria for determining if a geological feature was formed by a meteorite or comet impact. Key criteria include the presence of shatter cones, planar deformation features in minerals, high pressure polymorphs in minerals, and impact melt sheets and breccias. Morphology is also a criterion but can be complicated by erosion and other geological processes on Earth.

2. Megan Grove

3. A colored magnetic-anomaly map shows the Chicxulub impact crater, on the Yucatán Peninsula in Mexico. Scientists rely on such maps to help them study the crater, which is buried under more than half a mile (1 kilometer) of sediment. Anomalies (red, yellow, and blue) occur where the local magnetic field differs from the expected value (green). LiDAR works by shining a laser pulse at the ground and measuring the time delay of the returning light. The first light to get to you comes from the top of the canopy, and the last light to get back comes from the few photons that reached the ground before reflecting back. The distribution of light in between the first and last returns revealing details about the plant canopy structure. Nick

4. Chicxulub Crater, third largest and possible dinosaur killer. The third largest impact crater lies mostly underwater and buried underneath the Yucatán Peninsula in Mexico. At 170km (105 miles) in diameter, the impact is believed to have occurred roughly 65 million years ago when a comet or asteroid the size of a small city crashed, unleashing the equivalent to 100 teratons of TNT. Likely, it caused destructive tsunamis, earthquakes and volcanic eruptions around the world, and is widely believed to have led to the extinction of dinosaurs, because the impact probably created a global firestorm and/or a widespread greenhouse effect that caused long-term environmental changes. nick

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12. Megan Grove

13. ~ Scattering of dust and debris into the atmosphere ~ Cause large fires (generated by hot debris thrown from the crater) ~ Tsunamis, and severe storms with high winds and highly acidic rain ~ Seismic activity, and perhaps even volcanic activity Megan Grove

14. ~ Dust and debris thrust into the atmosphere can block most of the sunlight - This would lower surface temperatures globally - Those organisms dependent on photosynthesis would die out and Earth's oxygen levels would dramatically decrease both on land and in the oceans thus suffocating organisms unable to cope with lower oxygen levels. Megan Grove

15. ~ The impact may cause chemical changes in the Earth’s atmosphere - Increasing concentration of sulfuric acid, nitric acid, and fluoride compounds ~ The heat from the impact’s blast wave would have incinerated all life forms within its path Megan Grove

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23. Alex

24. Source: B612 Foundation