Part 1 Printing the Circuit Board. 1. Choose a method to use for creating the PCB. Your choice will usually be based on the availability of materials needed by the method, the technical difficulty level of the method or the quality of PCB you desire to obtain.
Permian-Triassic Extinction. In this video segment from Evolution: Extinction!, geologist Peter Ward shows rock layers laid down during the Permian and Triassic periods. The Permian layers contain abundant animal fossils and fossilized traces of animals, while the Triassic layers are almost devoid of fossils, suggesting a mass extinction event occurred 250 million years ago, at the end of the Permian.
The movement of Earth's tectonic plates formed Pangaea and ultimately broke it apart. Pangaea existed during the Permian and Triassic geological time periods, which were times of great change. The Permian mass extinction, which wiped out an estimated 96% species about 248 million years ago, was a major event during this time.