Rocks Layers????

Question

How can 200 year old rocks be formed on top of 100 year old ones.. like if for example, that type of situation was found... how could that have happened?

Answer 1

You could concievably uncover a small area where older rocks would be found above younger ones if the area had suffered some geologic upheaval where deep rocks had been blown out of the ground and landed on top of later layers, or where there had been a sudden uplifting...but there would likely be evidence that these rocks were no longer in thier original formations. If you had a plate moving under another plate, then the younger rocks on top of the plate that was moving under might be found below older rocks on the plate that was riding over it, but again, there would be evidence that these were plate edges...

Answer 2

A fold in the crust.

I was watching Fearless Planet on the Discovery Channel last night and they were in the mountains of Alaska and found fossils of sea creatures. They got there because the Rocky Mountains were uplifted by the collision of two continental plates.

Not all of the ground moves east to west some of the plates run north and south and others run under those. They have been doing this for billions of years and it is possible that what you see on top of a mountain was once at the bottom of the sea or that the rock layers you see were folded or bent or are even sticking straight up. The earth is dynamic and changing all the time. The ground is doing that in slow motion, but over billions of years look at all the changes that have been made. We went from one super continent to 7 and eventually China and California are going to run into each other.

Take a look at this Wikipedia article (http://en.wikipedia.org/wiki/Tetonic_plates) and you can see the plates are moving all around. Remember that if you looked at the earth like it was a basketball the hollow center would be all liquid and the surface of it would be like the crust. If that basketball was wet then the sheen of water on the surface of it would be like our atmosphere. By far the majority of our planet is molten rock and it is moving.

Answer 3

As has already been said, overturned folds can produce older rocks on top of younger ones (imagine rumpling up a tablecloth, and seeng s or z shaped folds form).

Alterntively, intruding magma into a prexisting rock (to form a sill) would poduce the sequence old rock-young rock-old rock.

Answer 4

100 years is an incredibly short time for overturning, if your ages are supposed to be important here, but they might not be. Some other examples might be if the younger rocks formed in a cave or cavern, or perhaps an overhang at the beach.

Answer 5

The short answer: overturning of rock beds due to seismic activity.

So the 200 year old rocks didn't form on top of the 100 year old ones (though rocks are much older than this), they formed first, but due to being "flipped" over by some sort or earthquake or faulting they look to be on top. Look up the law of superposition.