Relative age dating geology
Therefore, deeper layers must be older than layers closer to the surface. You can see an example in Figure below and at the link below.[Link about law of superposition here.] Rock layers extend laterally, or out to the sides.
The presence of more than one type of index fossil provides stronger evidence that rock layers are the same age. Geologists divide this time span into smaller periods. Which period of geologic time was the last in which dinosaurs lived? Why are sedimentary rocks more useful than metamorphic or igneous rocks in establishing the relative ages of rock?The laws of stratigraphy are usually credited to a geologist from Denmark named Nicolas Steno. Superposition refers to the position of rock layers and their relative ages.Relative age means age in comparison with other rocks, either younger or older.The way things happen now is the same way things happened in the past. Mountains grow and mountains slowly wear away, just as they did billions of years ago. They become extinct, meaning that they die out completely. They use clues from rocks and fossils to figure out the order of events.As the environment changes, living creatures adapt. They think about how long it took for those events to happen. The laws of stratigraphy can help scientists understand Earth’s past. Refer to the figure as you read about the laws below.
Erosion may have worn away some of the rock, but layers on either side of eroded areas will still “match up.” Look at the Grand Canyon in Figure below. You can clearly see the same rock layers on opposite sides of the canyon.