Relative dating is used to arrange geological events, and the rocks they leave behind, in a sequence. The method of reading the order is called stratigraphy layers of rock are called strata. Relative dating does not provide actual numerical dates for the rocks. Next time you find a cliff or road cutting with lots of rock strata, try working out the age order using some simple principles:.
Earth Science: Geologic Ages and Dating Techniques
Dating Fossils in the Rocks | National Geographic Society
Melissa graduated from NC State University with a Bachelor's Degree in geology in and currently works as a lab technician. Figuring out the geologic history of an area seems like a daunting task, but there are several strategies that geologists use to figure out which rocks are older than other rocks, and what geologic processes occurred in a particular order. Geologists can numerically date certain rocks by using the radioactive decay of elements trapped in rocks or minerals to figure out their exact age. However, these radioactive isotopes aren't always present in a rock, so geologists must use context clues to build a calendar called a geologic timescale of when each rock layer in a formation was created. Relative dating uses a series of 5 principles listed in the following paragraphs that help geologists compare the ages of different layers of rock and create a geologic timescale for an area. Most sediments that you see in rock formations are deposited in horizontal layers originally, due to the effect of gravity.
Lake Turkana has a geologic history that favored the preservation of fossils. Scientists suggest that the lake as it appears today has only been around for the past , years. The current environment around Lake Turkana is very dry. Over the course of time, though, the area has seen many changes.
Explore This Park. The eroded cliffs reveal 1. The oldest rocks exposed in the canyon are ancient, 1, million years old. Conversely, the canyon itself is geologically young, having been carved in the last 6 million years. An appreciation of geologic time places geologic topics such as geomorphology, the origin and evolution of the Colorado River, stratigraphy, historical geology, and paleontology in context.