Fossils and rock layers | The geosphere | Middle school Earth and space science | Khan Academy

Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now! Earth's history can be organized using the geologic time scale, which is based on evidence from rock strata and the fossil record. Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy…