Sedimentary rocks build up layers from the oldest deposits, at the bottom with the newest at the uppermost layers. Biostratigraphy is a specialized form of Stratigraphy, which uses plant and animal fossils to establish the different layers.There are four basic principals of Stratigraphy, which help us understand Earths time line. Non-horizontal layers have been folded or tilted after the original sedimentation.First, we must understand they are dating the rocks and other materials found on the Earth to determine this.There are two basic types of dating methods geologists rely on, Relative Time Dating and Absolute Time Dating.In the late 18 century, James Hutton developed the idea that the layers found in rock outcrops were representations of the story of time on the planet.
Stratigraphy: is the science or study of layers or strata of rocks.
This happens because of upheaval, earthquakes, or other large earth movements.