There had evidently been a wave of death, in which thousands of species had vanished from the world. No one has explained what happened-at least not to the general satisfaction. A drastic retreat of shallow seas may have destroyed innumerable environments. The cause may zakelijke energie have been extraterrestrial-lethal radiation from a supernova dying nearby. The wave of death occurred 250.1 million years before the present, and exactly that long ago flood basalts emerged in Siberia and quickly covered about a million and a half square kilometres with incandescent lava. The brief, intense greenhouse effect, the surge of carbondioxide emissions, would have stopped the upwelling of the oceans and the associated growth of nutrients. None of these hypotheses has attracted enough concurrence to be dressed out in full as a theory, but, whatever the cause, no one argues that at least half the fish and invertebrates and three-quarters of all amphibians-perhaps as much as ninety-six per cent of all marine faunal species-disappeared from the world in what has come to be known as the Permian Extinction. It was an extinction of a magnitude that would be approached only once in subsequent history, or-to express that more gravely -only once before the present day. The sharp line of creation at the outset of the Cambrian had an antiphonal parallel in the Permian Extinction, and the whole long stretch between the one and the other was set apart in histo1y as the Paleozoic era. It was zakelijke energie vergelijken a unit-well below the surface but far above the bottom-just hanging there suspended in the formless pelagics of time. The Paleozoic-544 to 250 million years before the present, a fifteenth of the history of the earth. Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian. When I was seventeen, I used to accordion-pleat those words, mnemonically capturing the vanished worlds of “Cosdmpp,” the order of the periods, the sequence of the systems. It was either that or write them in the palm of one hand.