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Some of these time lines were bolder than otl1ers, and none more so than the one tlrnt underlined the first appearance of megascopic fossils in abundance in the world. It marked a great and sudden explosion of life, all the major phyla having developed more or less at the same time and now acquiring skeletons and shells and teeth and other hard components that allowed them individually to be reported to the future. Because rock that held these early fossils was first┬ázakelijke energie studied on Harlech Dome and adjacent Welsh terrains, geologists named the system Cambrian, after the Roman name for Wales. They then named the Silurian for a Welsh tribe that bitterly defied the Romans. After some years and more comparative study, an argument broke out over tl1e Cambra-Silurian line, a scientific battle royal in which the Cambrian forces tried to move their banner fmward through time and the Silurian proponents attempted to push theirs back. The disputed block of time became a sort of demilitarized zone. Friendships came unstuck. The standoff lasted for decades, until some genius in scientific diplomacy suggested that the disputed time had enough characteristics of its own to be given the status of a discrete period, an appropriate name for which-in honor of another tribe of intractable Welsh belligerents-would be Ordovician. There was a lot of room for generosity. There was plenty of time for all. Cambrian-544 to 490. Ordovician-490 to 439. Silurian-439 to 408 million years before the present. A British geologist went to Russia and after a season or two’s tapping at the Urals named still zakelijke energie vergelijken another period in time, and system of rock, for the upland oblast of Perm. There were formations in Perm with a fossil story distinctly their own that were superimposed-as they happen to be in Pennsylvania, as they happen to be at the rim of the Grand Canyon-upon the Carboniferous. What was distinct about the character of the Permian assemblages was not only the forms to which they had evolved but also their absence in great numbers from higher, younger strata.

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