# Relative dating block diagrams

Sample **dating** is done by counting beads that represent 235U and 207Pb atoms in a zircon.

Students should be able to read x-y plots and divide two numbers.

As the amount of parent isotope decreases by radioactive decay, the amount of the daughter isotope increases commensurately.

Therefore, at any time, the total of parent isotope fraction and daughter isotope fraction add up to 1.

There are three parts to this lab: working with graphs and calculations to derive absolute ages based on the decay of radioactive isotopes, practice using the principles of **relative** geologic to determine age sequences represented on cross-sections and **block** **diagrams**, and applying **relative** geologic age principles to the geology of the Grand Canyon.We'll also discuss some basic laws of geology that can help scientists deduce both the order of events that create a landform and the geologic events that occur after a landform's formation. Usually, we study history, look for observations and evidence, and make some assumptions about what went on.Many of these ideas also hold true for scientists trying to figure out what happened to the earth in the past.For more information on these systems, see the isotopes and half-lives section of the Geologic Time Basics page.The Modern Geologic Time Scale, as shown above, documents intervals of geologic time **relative** to one another, and has been continuously developed and updated over the last two centuries.

### Search for relative dating block diagrams:

There is some ambiguity in the *block* diagram, so students must determine numerical ages for samples from the *block* diagram to test their *relative* age hypotheses.

People are looking for compatibility, and not for a one night fling - like you find at a bar (again, this is typically the case, not always).