Question

Analyze the evidence scientists provide for the cause of the Cretaceous–Paleogene mass extinction.

a. the unusual abundance of iridium in the Cretaceous-Paleogene layers, the disappearance of so many species at its transition, volcanic activity that led to global warming, and the crater found in the Yucatan peninsula

b. the unusual abundance of iridium in the Cretaceous-Paleogene layers, gamma-ray burst caused by a nearby supernova, rocks found in the clay layer at its boundary, and the crater found in the Yucatan peninsula

c. the unusual abundance of iridium in the Cretaceous-Paleogene layers, the disappearance of so many species at its transition, rocks found in the clay layer at its boundary, asteroid impact, and volcanic eruptions at large

d. the unusual abundance of iridium in the Cretaceous-Paleogene layers, the disappearance of so many species at its transition, rocks found in the clay layer at its boundary, and the crater found in the Yucatan peninsula.

Answer 1

The Cretaceous-Paleogene mass extinction is best understood through the evidence of a worldwide iridium anomaly, large-scale species disappearances, a unique sediment layer, and a colossal impact crater in the Yucatán Peninsula, all supporting the asteroid impact theory, with potential contributions from volcanic activity.

Step-by-step explanation:

The Cretaceous-Paleogene (K-Pg) mass extinction event is one of the most well-documented and widely studied extinctions in Earth's history. The primary evidence pointing to the cause of this mass extinction includes the unusual abundance of iridium in the sedimentary layers at the K-Pg boundary, the global disappearance of numerous species, a significant layer of rocks found in the clay at the transition boundary, and the discovery of a large impact crater in the Yucatán Peninsula. Iridium is a metal that is rare on Earth's surface but common in asteroids, and its elevated presence globally at the boundary layer suggests a massive asteroid impact. This layer also shows an increase in shocked minerals and microscopic glass spherules, which are indicative of a high-energy impact event. The presence of the Chicxulub crater in the Yucatán Peninsula aligns with this timeframe and provides strong evidence of an asteroid collision. The contributions from large-scale volcanic eruptions, such as those at the Deccan Traps in India, may have also played a role in the extinction, exacerbating the environmental stresses from the impact.