The geological transformation of Earth from 520 million years ago to the present has been marked by significant changes in tectonic plate configurations, climate, and life forms. Here is a summary of key periods and events: • 520 million years ago (Early Cambrian): This period is part of the Paleozoic Era. The supercontinent Rodinia had already begun to break apart, and the formation of new oceans and continents was underway. • 420 million years ago (Silurian): By this time, the continents were

49K views · 694 reactions | Volcanoes are as dangerous as they are majestic. Over 50 eruptions rock our planet every year. This video helps you understand what causes volcanoes to form and erupt—and shows where they are most likely to be found. | National Geographic TV | Facebook