This means that a quartz sandstone deposited 500 million years ago will look very similar to a quartz sandstone deposited 50 years ago.
Making this processes even more difficult is the fact that due to plate tectonics some rock layers have been uplifted into mountains and eroded while others have subsided to form basins and be buried by younger sediments.
We'll even visit the Grand Canyon to solve the mystery of the Great Unconformity!
Imagine that you're a geologist, studying the amazing rock formations of the Grand Canyon.
Based on our study of meteorites and rocks from the Moon, as well as modeling the formation of planets, it is believed (pretty much well-established) that all of the objects in the Solar System formed very quickly about 4.56 billion years ago.
When we age date a planet, we are actually just dating the age of the surface, not the whole planet.
Your goal is to study the smooth, parallel layers of rock to learn how the land built up over geologic time.
Now imagine that you come upon a formation like this: What do you think of it? How can you make any conclusions about rock layers that make such a crazy arrangement?
We can then use radioactive age dating in order to date the ages of the surfaces (when the rocks first formed, i.e. We also have meteorites from asteroids and can date them, too.These are the surfaces that we can get absolute ages for.For the others, one can only use relative age dating (such as counting craters) in order to estimate the age of the surface and the history of the surface.With out individual time stamps the process of dating these structures could become extremely difficult.To deal with many of these problems geologists utilize two types of geologic time: relative time and absolute time.With this in mind geologist have long known that the deeper a sedimentary rock layer is the older it is, but how old?