Select all that apply.
a. The K-T boundary in Zumaia, Spain is sharp–representing an abrupt change in the marine ecosystem.
b. The K-T boundary separates rock layers of the Cretaceous period from those of the Tertiary period.
c. The K-T boundary is a thin layer of clay found only in Gubbio, Italy.
d. The K-T boundary dates to 65 million years ago (when the dinosaurs disappeared).
The Correct Answer and Explanation is :
The correct answers are:
a. The K-T boundary in Zumaia, Spain is sharp–representing an abrupt change in the marine ecosystem.
b. The K-T boundary separates rock layers of the Cretaceous period from those of the Tertiary period.
d. The K-T boundary dates to 65 million years ago (when the dinosaurs disappeared).
Explanation:
The K-T boundary (Cretaceous-Tertiary boundary) is a geological marker that marks the end of the Cretaceous period and the beginning of the Tertiary period, approximately 65 million years ago. This boundary is notable because it coincides with the mass extinction event that wiped out a large portion of Earth’s species, including the non-avian dinosaurs.
- a. The K-T boundary in Zumaia, Spain is sharp–representing an abrupt change in the marine ecosystem.
This is correct because the K-T boundary represents a sudden and dramatic shift in ecosystems. In locations like Zumaia, the boundary is clearly marked by a sharp change in the types of species found, particularly in marine life, reflecting the sudden extinction event that occurred around this time. - b. The K-T boundary separates rock layers of the Cretaceous period from those of the Tertiary period.
This statement is also true. The K-T boundary is a significant geological transition that marks the end of the Cretaceous period (about 66 million years ago) and the beginning of the Tertiary period (which would later be subdivided into the Paleogene, Neogene, and Quaternary periods in modern times). - d. The K-T boundary dates to 65 million years ago (when the dinosaurs disappeared).
This is true as well. The K-T boundary is famously associated with the mass extinction event that led to the disappearance of the non-avian dinosaurs. This event is widely believed to have been caused by a combination of factors, including an asteroid impact and volcanic activity, leading to catastrophic environmental changes. - c. The K-T boundary is a thin layer of clay found only in Gubbio, Italy.
This statement is incorrect. While the K-T boundary can be marked by a thin layer of clay, it is found in multiple locations around the world, not just in Gubbio, Italy. The clay contains high levels of iridium, which is thought to have been deposited by the asteroid impact that triggered the mass extinction. However, it is not exclusive to Gubbio.