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An example of events expected to take place as a result of a Bolide impact in relation to the well documented K-T event


This is the sequence of events thought to have taken place. Firstly, as the impactor entered the earths atmosphere it generated a shock wave with immense heat from the friction caused. This heat caused oxides of Nitrogen to be formed and on mixing this with atmospheric moisture (clouds) Nitric acid rain was formed.


When the actual impact occurred it is has been calculated that the speed was ~ 16,000 Km/h, this speed and the size of the Comet are believed to have done several things. The first is that a blanket of melt material was instantaneously sent hurtling out of the crater; evidence of this is found all around this region and as far as Northern America as clasts of melt with very similar compositions known as Tektites (see diagram below). The force of the impact caused quartz present to re-structure its crystals to form shocked quartz. Tsunamis were the oceans response to the shock wave sent through the crust and upper mantle. These are thought to be triggered by huge sub-marine sediment slumps, as the rock record shows that there are massive singular flows across Northern America but not the whole world

Map showing the location of the impact site


The answer to the rest of the extinction event is the long-term effects and chain events occurring after the actual impact. The heat generated from penetration of the atmosphere and the heat wave generated from the sheet of molten material (Tektite) radiated throughout the global atmosphere and caused huge fires. After this occurred other, surviving vegetation was prone to the acid rain that had accumulated.


Finally, the prevention of photosynthesis due to blockage of sunlight by soot created from the global burning event reaching the stratosphere. This soot and fine material from the crater dropped down after about six months and provided the evidence by leaving Iridium rich rock anomalies ~ 1-2 cm thick worldwide which were discovered by Walter Alvarez in 1979 (Iridium anomalies only found in conjunction with impacts). The direct result of this was the halting of food production for Herbivores such as Triceratops; Carnivores such as Tyrannosaurus were satisfied for some time longer due to the carcasses of already dead herbivores providing sustenance, if that is they had managed to survive the other events such as fire. The best survivors at this time are therefore thought to be the smaller burrowing animals as they could hide from the fires and fallout material. These animals also tend to feed on small creatures such as the decayers, and at this time there was plenty of decaying material whether it be vegetation or an animal.


This series of events simply goes to show the actual record we find in rocks where the extinction as a whole was not all instantaneous but actually began at the time of impact and carried on until living things evolved or were made extinct because they could not evolve to the new living circumstances.

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