Prehistoric Asteroid-Collision on Earth
Scientists believe that 3.5 billion years ago an asteroid hit the earth leading to giant tsunamis. They have found traces of this event in some of the oldest known rocks. The giant tsunami would have possibly swept around the Earth several times; submerging and destroying everything except the mountains. The coastlines of the continents were also changed drastically and almost all life on land was destroyed completely. This catastrophe that took place some 3.5 billion years ago is the oldest known meteor strike to hit the Earth. It is also one of the four that have been identified in a 300 million year period.
Byerly and Xiaogang Xie, of the Louisiana State University, and Donald Lowe and Joseph Wooden of Stanford, have identified traces of the asteroid collision in some of the oldest known rocks on Earth, in South Africa and northwest Australia. When the asteroid actually hit the earth, it was vaporized by the extreme energy of impact. These vapours then condensed into droplets of melt which dropped into the sea for the next few days depositing as layers on the bottom of the sea.
Byerly said they do not have an exact idea as to where the meteor hit, but they believe it was probably some distance from where they found the condensed droplets. They also predict that the collision would have taken place in water rather than on land due to the reason that the condensed droplets lacked mineral composition that was expected from a droplet that would have vaporised on the land. The above research was explained by Byerly using a slab of greyish rock, in which layers of those condensed droplets could be seen interlaced with layers of fine sand or silt. It is expected that a tsunami takes around 30 hours from the time of impact to travel all around the world once, when finally it met itself back after 30 hours. It then again bounces back the other way again setting up harmonic waves. This was explained by the several thin layers of mud that had been depositing between the arrival of these tsunami waves.
Dinosaur Extinction Asteroid
This great tsunami would have submerged everything under water, leaving no life on land. Also this massive movement of ocean water would have changed the coastlines of the continents and also eroded most of the land masses. The heat of the collision would have been so high that it is likely to have evaporated at least the upper 30 to 300 feet of ocean water, thereby killing any living being on the surface or near the ocean surface, and all the living beings on the land.
Scientists believe that there was life on earth at that time, and if the meteor had a size of 20 miles in diameter, it would have definitely killed everything on the surface of the earth. The initial destruction would have been for the life in the ocean and places nearby the collision spot, due to the hot steam of molten rock and water, and then when tsunami occurred, the life on land would have been destroyed. But anything that survived would have been in deep rocks or below the surface of earth. Byerly came across these evidences while he was researching on ancient volcanic activities in Australia and South Africa. The fact that the inner solar system was knocked about and damaged twice is widely accepted. The assumption is, that the solar system was created by a cloud of dust and rocks that later on condensed into the sun and the planets with larger pieces falling near the end of the solar system. It is believed that this process completed 4.5 billion years ago.
Dinosaurs'extinction: The cause
About 3.8 million years ago the inner solar system was knocked by severe destruction, which can be proved by the crates found on Moon, Mars and Venus. The earth was also heavily damaged, but there is no evidence, since the oldest available rock on earth dates 3.5 billion years old.
Now a second destruction took place on earth 3.5 billion years ago, which has left evidences in the rocks that Byerly is studying, but this has not yet been well accepted. Byerly’s team are dating the events using an instrument at Stanford and this machine measures the decay of uranium into lead. Uranium was found in the zircons in both the Australian and south African sites. These zircons would have been formed due to volcanic activity and then got deposited in the impact layers when the tsunami washed over all the continents of the earth. This fact that the zircons of identical ages were found in two continents shows the world wide effects of the impact.
These impacts are predicted to happen probably once every 100 million years. These collisions are similar to the ones that killed the dinosaurs 65 million years ago, but they were 100 to 1000 times more powerful. According to the scientists, there can one such another event. Large asteroids get disturbed by interactions with Jupiter. When such an interaction takes place, they fall into the earth’s orbit and eventually strike the earth. But there are no predictions or calculations as to when the next collision would take place. The evidence of all this is contained on a greyish slab of rock that lies on Byerly’s desk.