how do you know if a rock is young or old?

Question

I need help. Please explain. I'll give out points.

THANKS!!

Answer 1

Check its ID.

But seriously, you can tell the age of a rock in several different ways. If you know where the rock came from, you can compare its age to the ages of other rocks in the same area. If you don't know their ages, you can use radiometric dating. That's when you compare the amount of radiation emanating from a rock with a known starting value. Since radioisotopes decay at a known and constant rate, you can extrapolate backwards to determine when the rock was formed.

If the rock contains fossils, you can find out when those organisms lived. Obviously the rock formed at that same time.

If a rock is volcanic in origin, I suppose you could find out where the nearest volcano is and when it last erupted. That might yield some results, but I would use another method as well.

Answer 2

Ask it to dance and see if it does the jitterbug.....

Rocks can be dated in a number of ways. If the rock is on a hillside, its age can be compared to the rocks that are above it and below it. How are those rocks dated? By looking at fossils in the rocks (which may have been dated by a number of means) and by looking at any byproducts of radioactive elements that may have been incorporated in the rocks as they formed. If the rock is not on a hillside, but perhaps on a river bank or in the middle of a field, the chemical and physical makeup of the rock can be compared with other simliar rocks in the area whose ages are known. Except for rocks containing radioactive elements whose halflives are known, and volcanic rock, whose formation was actually witnessed, the ages of rocks are usually described in ranges - 3-4 million years, 250-275 million years, etc. Dating rocks, rivers, oceans, and mountains is really like a giant puzzle. It takes a lot of time, effort, and people to put it all together.
Good Question.

Answer 3

Well you can date rock strata by the principle of superposition (older rocks on bottom, younger rocks on top). Or you can use index fossils. Sometimes rocks around the same age will have similar fossils in them so you know they're about the same age, but that only works with rocks that have index fossils.

Also there's radiometric dating. That's basically observing how much of the mineral there is, and comparing it to their decay rates.

Answer 4

Potassium Argon dating is used to date rocks.
One may conduct field tests, older rocks in bottom layers if they run horizontal, however, uplifting and tilting may deposit old rock on the surface through erosion.

Answer 5

Just ask it.

Lol