AP BIOLOGY

Detailed explanation-1: -It is based on the Law of Superposition which states that in undisturbed rock sequences the bottom layers are older than the top layers. Therefore, some discovered fossils are able to be dated according to the strata, a distinct layer of rock, that they are found in.

Detailed explanation-2: -When, over a long time, layers and layers of sediments get deposited on top of each other, the weight of the top layers presses down on the bottom layers, forming them into rock called sedimentary rock. The oldest layers are on the bottom, and the youngest layers are on the top.

Detailed explanation-3: -This is called the Law of Superposition in geology. Students in the above images, you see that older layers are on the bottom and therefore the animal fossils found in those older layers are therefore older animals. More recent organisms are found on the top layers.

Detailed explanation-4: -Over time, the sediments pile up to form horizontal layers of sedimentary rocks. The bottom layer of rock forms first, which means it is oldest. Each layer above that is younger, and the top layer is youngest of all.

Detailed explanation-5: -As rocks at the earth’s surface are broken down, or “weathered, ” the sediment is moved by forces such as water and wind and deposited elsewhere in layers. Over time, these layers build up and solidify, becoming sedimentary rock. Organisms can be preserved as fossils if their bodies are buried within these layers.