What is relative dating of rocks and fossils
"Radiometric dating" gives you an exact date of formation for a layer or a rock, even if you don't have another layer or rock to compare it with.Discover how geologists study the layers in sedimentary rock to establish relative age.
The age is based on the half-life of the isotopes (their rate of decay over time).Relative dating requires an extensive knowledge of stratigraphic succession, a fancy term for the way rock strata are built up and changed by geologic processes.You may already know how to date a fossil with a rock. Students not only want to know how old a fossil is, but they want to know how that age was determined.Some very straightforward principles are used to determine the age of fossils.Back in 1793, there lived a land surveyor named William Smith.
The Permian through Jurassic stratigraphy of the Colorado Plateau area of southeastern Utah is a great example of Original Horizontality and the Law of Superposition, two important ideas used in relative dating.
But sometimes, a scientist finds a couple of rock outcrops that are separated by a wide distance.
One outcrop shows layers from one geologic time period, while the other outcrop represents a different time. Can he put the pieces together to make the story more complete? Let's find out how scientists deal with this common problem by using the fossils inside the rocks.
Students should be able to understand the principles and have that as a background so that age determinations by paleontologists and geologists don't seem like black magic. Geologists in the late 18th and early 19th century studied rock layers and the fossils in them to determine relative age.
William Smith was one of the most important scientists from this time who helped to develop knowledge of the succession of different fossils by studying their distribution through the sequence of sedimentary rocks in southern England.
You should already understand that the lower rock strata are generally older than the strata found higher up in the rock.