Define relative age dating meet friends for dating
So I can say the second layer is younger than the first and older than the third but I have no idea whether the cake is 5 minutes or 5 million years old.Relative dating is used commonly when looking at the relative order of geological events.The more fossils you find at a location, the more you can fine-tune the relative age of this layer versus that layer.Of course, this only works for rocks that contain abundant fossils.What can complicate relative dating is when the strata is not the right way up!
Long before I understood what any of it meant, I'd daydream in science class, staring at this chart, sounding out the names, wondering what those black-and-white bars meant, wondering what the colors meant, wondering why the divisions were so uneven, knowing it represented some kind of deep, meaningful, systematic organization of scientific knowledge, and hoping I'd have it all figured out one day.
Major boundaries in Earth's time scale happen when there were major extinction events that wiped certain kinds of fossils out of the fossil record.
This is called the chronostratigraphic time scale -- that is, the division of time (the "chrono-" part) according to the relative position in the rock record (that's "stratigraphy").
Paleontologists have examined layered sequences of fossil-bearing rocks all over the world, and noted where in those sequences certain fossils appear and disappear.
When you find the same fossils in rocks far away, you know that the sediments those rocks must have been laid down at the same time.
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We have no idea how much older thing B is, we just know that it's older.