Geochronology, dating and precambrian time. The beginning of the world as we know / Геохронология, датировка и докембрийское время. Начало мира, каким мы его знаем

Planet Earth was formed roughly 4.6 billion years ago. For human beings—used to measuring time in terms of days, weeks, and months—such an enormous span of time can be a difficult concept to grasp. Geologists, scientists who study the Earth and the processes that continue to shape it, have broken up this vast expanse of “deep time” into major divisions based on what they have learned from the study of ancient rocks and fossils. The first of these divisions—from approximately 4.6 billion until 542 million years ago—is known as the Precambrian, meaning everything that happened before the Cambrian period. (Today some people prefer to call this period the Cryptozoic, which means “hidden life.”) Almost all of planet Earth’s history is Precambrian. Until recently, however, it has remained the most unknown, the strangest, and most perplexing period in all geologic

history—what some have referred to as the “Dark Ages” of Earth’s existence. <...>