The K/T Boundary, Dinosaurs, Iridium. A Strange Brew Indeed!

Surely everyone knows about dinosaurs, right? Reptiles? No, they were not, no matter what you heard. Nor did man made global warming kill them. But I know what did, thanks to scientists Luis and his son Walter Alvarez. Read about the Alvarez hypothesis here. But it's not mere theory to me...it is fact.

Earth's time, measured on the massive scale of "geologic time," is divided into various epochs or eras. Each era is millions of years in length and they are generally separated by some sort of geologically discernible event or marker known as a boundary layer or event marker. The K/T Boundary is one of these geologic markers. Below the boundary layer can be found the remains of fossilized dinosaurs that ruled the Earth for some 160 million years before the event or series of them that ended the reign of these leviathans. Read more here.

And hidden in the K/T Boundary layer is a thin, tightly packed layer of dark sediment that is rich in the element iridium. Iridium is found on planet Earth in very tiny quantities, but the K/T Boundary layer has a concentration of iridium that is exponentially more plentiful than is found in other layers of Earth's sediments. And it's thanks to the Alvarez team that questioned why this layer of iridium was there, how it got there and how did that situation play into the end of the Cretaceous Era?

Iridium, for all it's scarcity on Earth below the K/T Boundary, is plentiful in asteroids. The Alvarez team reached the conclusion that a major asteroid impact deposited the layer of iridium. This layer of iridium at the K/T Boundary is found all over the world and whenever dinosaur fossils are found they are always below the K/T Boundary layer of iridium. The conclusions were inescapable. It wasn't a stretch except in the mind of some "settled science" (a bad idea if ever there were one, for nothing is ever actually settled) folks that the iridium was a fingerprint for a larger event. Now they had to determine what that event was.

The Alvarez's reached the conclusion that a large asteroid struck the Earth about 65.5 million years ago. But where was the evidence? Guess how the evidence of a large, epoch ending asteroid was found? Oil exploration! The drilling of test wells and geologic studies found something off kilter. At, as well as off of the northern tip of the Yucatan Peninsula in Mexico was found a huge geologic anomaly. It was the lip of a huge crater. Tests were conducted and the size of the crater began to emerge.

It is some 100+ miles across. It lay on the ocean floor of the Gulf of Mexico. Around it were found the telltale signs of ejecta...matter that is "ejected" from the crater and piled up around the lip. More study revealed the age of the crater to be 65.5 million years old. For a crater that size it would take an asteroid about 6 miles across striking the Earth at a somewhat oblique angle and the time of the strike and its size fit very nicely into the Alvarez theory. Another fingerprint of an impact were plentiful amounts of "shocked quartz" which are typical of exceptional heat and pressure and these are found at known impact sites worldwide.

When all the elements were added the conclusion was near inescapable. A six mile wide rock, one from deep space and rich in iridium, struck the northern tip of the Yucatan in a place we now call Chicxulub. See it here. The evidence was in. It was plentiful, convincing and after years of study, nearly indisputable. And "nearly" indisputable means room for disagreement. There are those who claim the Chicxulub impact wasn't sufficient to do the damage attributed to it. Most disagree with that position, but it is still a valid one.

What isn't in dispute is that the age of the crater is 65.5 million years. As well the following things are not in dispute: dinosaur fossils ARE NOT found above the K/T Boundary; iridium is scarce on Earth naturally, but plentiful in the layer of sediment that a huge asteroid strike would eject into the atmosphere; the age of the iridium layer matches the age of Chicxulub...65.5 million years.

Thanks to modern computer modeling we can now see what the Chicxulub impact might have looked like. The asteroid struck at an oblique angle and believe it or not, this as well as the location of the strike played a huge part in all that came after. The Earth's crust was of just the right density and makeup to exaggerate and magnify the asteroid impact. It is known such an impact would launch millions of tons of rock and debris into the atmosphere. It is assumed such a concentration of debris would have created a "nuclear winter" of darkness. Plants would not grow. Plant eaters would perish and with them soon after would perish the meat eaters who preyed upon the plant eaters.

When all the elements are added there seems to be a smoking gun. A six mile wide asteroid struck the tip of the Yucatan. It hit in just the right place and at just the right angle to eject so much soil and rock into the atmosphere to darken the planet and cause plants to slow growth. Those animals that lived on the mega flora died, and soon the dinosaurs that ate them died as well. It is said no animal bigger than a large domestic house cat survived the impact and aftermath. The historical date of the impact matches the end of the reign of dinosaurs and the telltale signs of iridium and shocked quartz all fit the scenario near perfectly.

In fairness though there are those who argue many other hypothetical ends to the dinosaurs. Some argue the dinos were already stressed by environmental change, disease and other non-impact factors. This may be true as well, but there is no doubt the Chicxulub Crater is real, large enough to have done what is theorized and is timed exactly right to be a huge contributing event in the dinosaurs end, regardless of any other factors.