The volcanic material in tuff is well-suited for radiometric dating, which uses known decay rates for specific unstable isotopes to determine the age of the rock that contains that isotope. Feldspar crystals found in the tuff layers contain an unstable isotope of potassium that can be used for this dating method.

What type of rock is best for dating fossils?

Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years. So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.

What are fossil rocks called?

Fossils are prehistoric hard-rock remains or traces of plants or animals preserved in sedimentary rocks. Although fossils are found throughout the world, theyre not commonly found in all types of rocks, but generally only in sedimentary rocks such as sandstone, limestone or shale.

Are fossil rocks?

Fossils are the preserved remains, or traces of remains, of ancient organisms. Fossils are not the remains of the organism itself! They are rocks.

How do you find a fossil in a rock?

Good places to find fossils are outcrops. An outcrop is a place where old rock is exposed by wind and water erosion and by other peoples digging. Make sure that you plan to dig in a place where it is okay to collect fossils. Check with an adult if youre not sure.