Final answer:
The K-Pg extinction event was caused by an asteroid impact, which led to global atmospheric changes and ecosystem collapse, causing mass extinction. Evidence includes a layer of iridium-enriched sediment and the discovery of a corresponding impact crater.
Step-by-step explanation:
Sequence of Events Following an Asteroid Impact
The K-Pg extinction event, or the Cretaceous-Paleogene mass extinction, was a cataclysmic event that occurred around 65 million years ago, resulting in the sudden disappearance of approximately three-quarters of the Earth's plant and animal species, including the dinosaurs. Following the impact of an asteroid, several events unfolded:
- A massive asteroid struck the Earth near the present-day Yucatán Peninsula, releasing energy on an unprecedented scale.
- The impact created a gigantic crater and propelled vast amounts of dust, soot, and debris into the atmosphere.
- As a consequence of the debris cloud, sunlight was blocked, leading to what can be described as an 'impact winter'. This blocked photosynthesis, which is essential for the food chain, causing a collapse in ecosystems.
- The massive release of sulphur aerosols and other toxic gases caused acid rain and further global cooling.
- Food chains collapsed, leading to the extinction of numerous species on land and in the oceans.
These factors contributed to the catastrophic effect on the planet's biodiversity. Evidence for this impact includes a worldwide layer of sediment enriched with iridium and other asteroid-related elements, as well as a large impact crater corresponding in age to the extinction event. The after-effects, such as a prolonged 'nuclear winter' and disrupted climate patterns, would have been detrimental to the survival of remaining species over the subsequent years and possibly decades.