What is the K-T Boundary?
The correct answer and explanation is :
The K-T Boundary (Cretaceous-Tertiary Boundary) is a significant geological event that marks the transition between the Cretaceous and Tertiary periods, about 66 million years ago. This boundary is especially famous because it corresponds with the mass extinction event that wiped out approximately 75% of Earth’s species, including the non-avian dinosaurs. It is also known as the Cretaceous-Paleogene (K-Pg) boundary in more modern terminology, reflecting updated classifications for the geological time periods.
The K-T Boundary is characterized by a distinct layer of rock, often referred to as the K-T layer, which is found worldwide in the geologic record. This layer contains high concentrations of iridium, a rare metal commonly associated with meteorites. The presence of iridium has led scientists to hypothesize that an asteroid or comet impact was a major cause of the mass extinction event. This hypothesis is supported by the discovery of the Chicxulub crater on the Yucatán Peninsula in Mexico, which dates to the same period.
This impact would have caused massive fires, tsunamis, and climate disruption, leading to a “nuclear winter” effect where dust and debris blocked sunlight, drastically lowering global temperatures and disrupting ecosystems. The resulting environmental changes would have been catastrophic for many species, particularly the large dinosaurs that could not adapt to the rapid climatic shifts.
In addition to the impact hypothesis, there are other theories that may have contributed to the extinction event, such as volcanic activity (e.g., the Deccan Traps in India) and changing sea levels. However, the impact remains the most widely accepted explanation for the sudden extinction.
The K-T Boundary represents a pivotal moment in Earth’s history, leading to the extinction of many species and the eventual rise of mammals, including humans, in the following epochs.