In this lesson we'll discuss both absolute and relative time, and how they work together to give us a detailed history of Earth.How much of your life do you spend thinking about time? Time comes in different forms in geology, mainly absolute and relative.In this case, the uranium is called the parent and the lead is called the daughter element. It is not affected by temperature, pressure, or other physical changes.
This change, over time, is called radioactive decay.But instead of saying that one layer is x number of years old, you can simply describe it as older than the layer above it yet younger than the layer below it.Relative age starts from the bottom and works upward.Just like we know that dinner comes after lunch even though we may not know what time it occurs.When we put both absolute and relative time together, we create a geologic time scale.So relative to the other meals, it falls in the middle and is later than breakfast yet earlier than dinner.This is useful in geology because you can age layers of rock relative to other layers.Here, we are looking at events relative to other events.For example, instead of pm we might say 'lunch time.' There is no definitive time for lunch, except that it occurs between breakfast and dinner.Rocks relate to events in Earth's history, and we can use them to put together a timeline that shows us both the order of events as well as when and for how long they occurred. We have over 95 college courses that prepare you to earn credit by exam that is accepted by over 2,000 colleges and universities.You can test out of the first two years of college and save thousands off your degree.