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Meteorite Impact and Dinosaur Extinction
Evidence is increasingly becoming available to us about meteorites, and the impacts that they have had as well as the effects that they have had on our earth. Such impacts continue to create a natural hazard to life on earth. Two times so far, in the twentieth century, large meteorite objects are known to have collided with our planet earth.
If there is an impact that is large enough, it could possibly disturb the earth’s entire environment. It could also cause an ecological catastrophe.
65 million years ago, at the end of the Cretaceous period of geological history, we were able to document this very type of impact. This break in the earth’s history is marked by a mass extinction, when at least half the species on the planet became extinct.
There are of course many, mass extinctions in the geological record, but the cretaceous mass extinction has been of utmost interest to paleontologists because it marks the end of the age of dinosaurs. For tens of millions of years, dinosaurs had flourished on this earth, and then suddenly they disappeared.
A meteorite with a mass of more than a trillion tons and a diameter of ten kilometers was the body that impacted the earth at the end of the Cretaceous period. Scientists first identified the impact in 1980, when they discovered a worldwide layer of sediment that was deposited from the dust cloud that covered the planet after the impact. This layer of sediment is enriched in the rare metal, known as iridium as well as other elements that are found in meteorites, but are found very rarely in the crust of the earth. By 1990, geologists had found the very site where the meteorite impacted the earth in the Yucatán region of Mexico. The crater, now deeply buried in sediment, was originally 200 kilometers in diameter.
This impact released an enormous amount of energy, creating an extremely large crater. The explosion lifted about a hundred trillion tons of dust into the atmosphere, as we have been able to determine by measuring the thickness of the sediment layer formed when this same dust settled to the surface. Such a quantity of material would have completely blocked out the sunlight from reaching the surface, sending the Earth into a period of cold and darkness, which lasted several months. Scientists also calculated that this explosion would have produced vast quantities of nitric acid and melted rock that sprayed out over much of the earth. This started widespread fires that would have consumed most terrestrial forests and grassland. These environmental disasters may have been responsible for the mass extinction, including the death of the dinosaurs.
There have been several other mass extinctions that have been identified with large impacts, but the Cretaceous event was so far the most dramatic. Even without actual documentation, it is clear that impacts of this size have occurred, and that their results can be catastrophic. However, what is a catastrophe for one group of living things may create opportunities for another group. After each mass extinction, follows a sudden evolutionary burst, as new species begin to develop to fill our ecological system.
Global catastrophes can be caused by impacts made by meteorites. This can seriously influence the evolution of life all over the planet. It is estimated that the majority of all species who have become extinct are due to such impacts. This ideology fundamentally changes our view of biological evolution. Species are able to survive if they can compete with other species and slowly adapt to changing environments. An equally important aspect of a species being able to survive is these species, being able to overcome these global ecological catastrophes, which are caused by impacts.
The earth is a target in a cosmic shooting gallery. It is open to random violent galactic events, which could not have even been conceived a few decades ago. In 1991, the US Congress had asked NASA to investigate the hazard, which large impacts could have on our earth. The scientists who were conducting the study analysed the impacts from the meteorites and concluded that they are indeed hazardous. There is always some risk that a large impact could still occur, studies are showing that the risk is quite small.
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- Question 1 of 10
The word ‘collided’ in paragraph one is closest in meaning to:CorrectIncorrect
- Question 2 of 10
In paragraph three of the passage, why does the author include the information that dinosaurs had flourished on earth for tens of millions of years and then suddenly disappeared?CorrectIncorrect
- Question 3 of 10
The word ‘catastrophe’ in paragraph two is closest in meaning to:CorrectIncorrect
- Question 4 of 10
Which of the following statements can be understood from the context of paragraph four, about the meteorite impact in Mexico?CorrectIncorrect
- Question 5 of 10
The word ‘consumed’ in paragraph five is closest in meaning to:CorrectIncorrect
- Question 6 of 10
In paragraph five; according to the author, all of the following statements are true regarding the impact at the end of the Cretaceous period except:CorrectIncorrect
- Question 7 of 10
The word ‘extinction’ in paragraph five is closest in meaning to:CorrectIncorrect
- Question 8 of 10
Which of the following statements is supported by what the author writes in paragraph seven about the factors that are essential for a species to survive?CorrectIncorrect
- Question 9 of 10
What does a paleontologist do?CorrectIncorrect
- Question 10 of 10
According to the author, who conducted the investigations about the modern day damages that could happen by a large meteorite impacting the Earth?CorrectIncorrect