deposited under conditions of normal polarity and then measuring successive layers, we can build a time chart. By matching different charts from different areas with similar fossils, a more global correlation can be made.These techniques led to the discovery of the boundary between the two eras. A single thin layer of clay found within predominantly limestone rocks established this. By comparing the marine life found in, above, and below the clay, the marine life, like the dinosaurs, had been terribly affected by the extinction event. The percentage of life in the upper layers was dramatically lower than that in the lower. This was far more compelling than what was suggested by dinosaurs fossils.Other samples of the clay were taken to laboratories to be analyzed. Part of the results showed a large concentration of platinum and iridium. These elements are very rare on the surface of the earth at the moment but they are present in meteoric dust that rains down from space at a known rate. That rate allowed for a measurement of how long it took for the clay to form.Surprisingly, the clay held almost 30 times more iridium than the limestone layers above and below the clay. Similar layers in other parts of the world gave the same results. The conclusion was that a giant meteorite hit the Earth 65 million years ago and had released a large amount of the elements into the atmosphere. This was then dispersed throughout the atmosphere and fell to the Earth as sediment. A connection was made between the meteor impact and the extinction of the dinosaurs and other species on Earth. The layers evidence showed that all life on the planet was influenced to some degree. IMPACTThis evidence helped established the boundary between the Crustaceous and the Tertiary. Referred to as the K/T Extinction event. (K stands for Crustaceous and T stands for Tertiary.) Now this leads us to search for evidence of impact.While scientists agree that some ...
