Dinosaur Extinction From Volcanic Eruptions
There are various theories why dinosaurs became extinct at the end of the Cretaceous period, about 65 million years ago. One theory holds that dinosaurs were killed by a series of massive and long lasting volcanic eruptions that poisoned the Earth's atmosphere and rendered the climate unsuitable for the dinosaurs. Geologic evidence suggests that volcanic eruptions can have strong effects on the earth's climate. Dust, debris and ash from volcanic eruptions can float in the atmosphere for a long time, perhaps many years. This particulate matter also reflects sunlight and it is then unable to reach the surface of the Earth. This causes the atmosphere to cool down and there is a corresponding change in climate from warm to very cold with winter-like conditions.
Additionally, gases that issue from the earth during an eruption can subtly change the balance of the composition of the atmosphere and cause like effects. Together, the thinking goes, the changes in the temperature and atmosphere from volcanic activity caused the earth to become, for an extended period of time, an exceptionally uncomfortable place. Before the Cretaceous period, the earth was very warm and very hospitable for plant life; afterwards, with the chilling effect of the eruptions, the plants were very likely killed due to the cold conditions. The dinosaurs were unsuited for the intemperate climate and, with the widespread loss of plants, those dinosaurs that were plant eaters were pushed to extinction. This, the theory goes, caused the meat eating dinosaurs to suffer similar catastrophic effect as there simply was not enough food.
The evidence for these volcanic eruptions is found in the geologic record. In modern day India, for example, there are lava flows from these ancient volcanic eruptions that dwarf any volcanic activity that modern man has ever known. The lava may have been greater than 1 mile thick in some places and covered more than 200,000 square miles. The corresponding fossil record seems to indicate, in at least some cases, that the dinosaurs became extinct gradually and over an extended period of time--which is exactly what one would expect if the Earth's climate gradually cooled.