The crater measures 180 kilometers across, and occurred about 65 million years ago. This is a massive impact crater buried under Chicxulub on the coast of Yucatan, Mexico. Researchers now think that the asteroid strike that created the K-T boundary was probably the Chicxulub Crater. That blocked photosynthesis in plants – the base of the food chain – and eventually starved out the dinosaurs. When that asteroid struck the Earth 65.5 million years ago, it destroyed a region thousands of kilometers across, but also threw up a dust cloud that obscured sunlight for years. They estimated that the impactor must have been about 10 km in diameter, and release the energy equivalent of 100 trillion tons of TNT. At the Cretaceous Tertiary Boundary, a major hiatus of varying time span of <1 to >30Ma is documented in several parts of the Cauvery basin by Raju et al.The researchers were even able to estimate what kind of asteroid must have impacted the Earth 65.5 million years ago to throw up such a consistent layer of debris around the entire planet. When they compared the concentrations of iridium in the K-T boundary, they found it matched the levels found in meteorites. Iridium is rare on Earth because it sank down into the center of the planet as it formed, but iridium can still be found in large concentrations in asteroids. When physicist Luis Alvarez and geologist Walter Alvarez studied the K-T boundary around the world, they found that it had a much higher concentration of iridium than normal – between 30-130 times the amount of iridium you would expect. Geologists have dated this period to about 65.5 million years ago. So the K-T boundary is the point in between the Cretaceous and Tertiary periods. What is the K-T boundary? K is actually the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period. What’s the evidence for this asteroid impact? A thin dark line found in layers of sediment around the world evidence that something devastating happened to the planet 65 million years ago. It was this event that pushed the dinosaurs over the edge into extinction. But in the last few decades, a new theory has arisen an asteroid strike millions of years ago drastically changed the Earth’s environment. Maybe the global climate changed, maybe they were killed by disease, volcanoes, or the rise of mammals. Text by Steve Smith.What killed the dinosaurs? That’s a question that has puzzled paleontologists since dinosaurs were first discovered. Up in the northwest corner you can find creative people in places like Portland and Seattle, along with awesome snowboarding and good beer. That is to say, the West Coast functions as the imagination of the US, like a weird little brother who teases everybody then gets famous for making freaky art.The central part of the country is flat farmland all the way over to the Rocky Mountains. California is full of nothing but grizzly old miners digging for gold, a few gangster rappers, and then actors. Here's a cemetery in Georgia where you can find graves of soldiers from the Civil War.The West Coast is sort of like another country that exists to make the east coast jealous. Southerners tend not to trust people from "up north" because they talk too fast. Probably they move slowly because it's so hot. Take a look at these rolling hills carpeted with foliage along the Hudson river here, north of New York City.The American south is known for its polite people and slow pace of life. Thirteen British colonies fought the American Revolution from here and won their independence in the first successful colonial rebellion in history. Patrick's cathedral in New York to Mount Hollywood California.The Northeast region is where it all started. The United States is one of the most diverse countries on earth, jam packed full of amazing sights from St.
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