Fossil succession relative dating
Yet his principle of fossil succession became the underpinning of much of our understanding about how dramatically Earth’s climate, continents, and life itself have changed over time.
Smith realized that certain rock layers contained certain types of fossils.Applying Steno’s Laws and the Principle of Faunal Succession led to the creation of a relative chronology of Earth history, or the geologic time scale.As a member, you'll also get unlimited access to over 55,000 lessons in math, English, science, history, and more.Thus was born the idea that certain types of fossils existed for a specific period of time in Earth history and that the layers of rock bearing these fossils could be correlated, or equated to one another, even over great geographic distances.The Smith-Cuvier discoveries are termed the “Principle of Faunal Succession” which says that fossils and groups of fossils exist for limited amounts of time, and that fossil plants and animals appear in the rock record in a definitive pattern.The short book contained plates—each colored to approximate the shade of the strata—with illustrations of fossils typically found in many of the layers he mapped.
Craig (or Crag, top) is a mixture of sand and shells found in Norfolk and Suffolk counties.
Among the evidence that Alfred Wegener provided for his theory of continental drift was that rock strata laid down at the same time in Africa and South America contained identical fossils—even though today they are on opposite sides of the Atlantic.
The influence of faunal succession would also eventually affect biology.
“All of us are using the Principle of Faunal Succession,” she says.
Fossils don’t just allow scientists to date rock layers, but also to uncover past climates, some of which differ dramatically from today’s.
Jerry Ortmans’ Stone Column features the same types of rocks originally delineated by Smith over 200 years ago (top to bottom): Chalk, Forest Marble (two blocks), Great Oolite, Inferior Oolite, Blue Lias (deeply scored), White Lias (two blocks), and Pennant Stone.