6 rules of relative age dating
Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.Pretty obvious that the dike came after the rocks it cuts through, right?Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old.To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.Men, in contrast, are hypothesized to be most attracted to women in their reproductive prime, which tends to be when they are younger. Women’s preferences, on the other hand, hold relatively constant across their lives, not going more than a few years below their own age (extra-credit if you can identify the “cougar zone” in this figure), but women remain keen on men up to 10 years older than themselves. However, younger men (i.e., in their 20’s) tend to be married to someone of a similar age, but as they get older their wives get younger.For example, by their 50’s the average male has a wife who is 10 years younger than him.
If you dump that water into a bowl, the surface remains flat.
For example, you can look in a stream and see ripple marks in the sand, formed by the flow of water over the sand.
If you see ripple marks in the rock record, you can know that a similar process was at work.
Image - three examples of depositional environments with tie points to show spacial correlations.
Unlike people, you can’t really guess the age of a rock from looking at it.