Relative age means age in comparison with other rocks, either younger or older. The relative ages of rocks are important for understanding Earths history. New rock layers are always deposited on top of existing rock layers. Therefore, deeper layers must be older than layers closer to the surface.

Which is the most important in determining the relative age of a rock body?

First and foremost, they use the law of superposition to determine the relative ages of sedimentary rock layers. According to the law of superposition, in horizontal sedimentary rock layers the oldest is at the bottom. Each higher layer is younger than the layer below it.

Is it important to know the age of fossil?

Determining the ages of fossils is an important step in mapping out how life evolved across geologic time. Biostratigraphy enables scientists to match rocks with particular fossils to other rocks with those fossils to determine age. Paleontology seeks to map out how life evolved across geologic time.

What can fossils and rocks tell us?

Fossils give us information about how animals and plants lived in the past. Some animals and plant are only known to us as fossils. By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other.